Figure 6 "diagrammatically illustrates three stages in the method of lifting employed with the illustrated hoists":
The Specification states that:
"Knee location abutment means are provided by a knee pad ... mounted on the front of the column ... for engagement with the knees of the patient ... during initial positioning of the hoist and during lifting, ...." (emphasis supplied)
It also states, in a passage on which Nesbit relies:
"As will be appreciated by those skilled in the art the lifting arm arrangement ... extends from the column ... for a somewhat shorter distance than is the case with conventional invalid hoists, approximating in length to the thigh length of a typical patient. Thus the main raising movement approximates to a more-or-less parallelogram motion, with the two lower pivots thereof provided by the knee and hip joints of the patient." (emphasis supplied)
The Specification explains Figure 6 in these terms:
"Figure 6 diagrammatically illustrates the lifting method of the invention as applied with the illustrated hoists. The hoist is brought up to the seated patient as shown in Figure 6(a) so that the knee abutment means KA locates against the knees of the patient. With the hoist correctly located relatively to the seated patient P, the feet of the latter are placed on the footplate or footrest means F; and the support sling S is passed around the body of the patient P below the armpits and attached to the lifting arm LA of the hoist. Raising of the lifting arm LA, typically through an angle of about 60o, so that the sling attachment points AP move through an arc A about a centre C located relatively to and positioned above the [footrest] means F, raises the patient P to the standing position shown in Figure 6(c). An intermediate position of the patient P, at the halfway point in the raising movement, is shown in Figure 6(b).
As Figure 6 clearly shows, a parallelogram lifting action occurs with a substantial part of the patient's body weight is [sic] at all times supported through the feet. The four pivot points of the parallelogram are respectively provided by the centre C, the sling attachment points AP, the knees and the hip joint of the patient P. To achieve such an approximately parallelogram movement the length of the lifting arm LA when not adjustable is made approximately equal to the thigh length of an average person. Any necessary adjustment to suit short or tall patients can be achieved by using an appropriate effective length of sling S.
The lifting of an infirm or severely disabled person is illustrated in full lines in Figure 6, as shown the knee region engaging the abutment means KA at all times even when in the final standing, and slightly backwardly-inclined, position. However, patients with sufficient muscular strength will involuntarily straighten their legs during lifting so that, in the final position the body is completely straight between the footrests or footplate F and the sling S. Thus for these patients the abutment means KA merely provide location at the initial stage of the lift." (emphasis supplied)
The second last paragraph prior to the statement of the claims is important:
"In the preferred hoist embodiments which have been described and illustrated the footrests (footplate), the knee abutment and the lifting arm pivot all remain stationary and in fixed relative positions. However, it will be clear from a study of Figure 6 that this is not necessarily so and that various relative movement can be employed to move from the initial condition of Figure 6(a) to the final condition of Figure 6(c), providing the movement of the sling attachment points AP occurs along the arc A relative to the footrests (footplate) F."
The Specification makes 31 claims. Claims 1-5, 28 and 31 are "method" claims. The remainder, claims 6-27, 29 and 30, are "apparatus" claims. Claims 2-5 depend on claim 1; claims 7-10 depend on claim 6; and claims 12-27 depend on claim 11. It follows that the independent claims are method claims 1, 28 and 31 and apparatus claims 6, 11, 29 and 30. In their claim of infringement, Impro-Arjo relied only on apparatus claims 6 and 11 and the parties' submissions before the trial Judge and on the appeal were, in substance, addressed only to those two claims. Although Impro-Arjo did not rely on claims 1-5, 7, 28, or 31 in their claim of infringement, they supported those claims in opposition to Nesbit's cross-claim for revocation.
The learned trial Judge set out all thirty-one claims in his Reasons for Judgment. I set out below, in addition to the critical claims 6 and 11, claims 1, 4, 5, 7 and 10 (emphasis supplied):
"1. A method of lifting a patient from a seated to a substantially standing position employing a hoist with a lifting arm arrangement presenting laterally spaced sling attachment points which are rigidly located laterally of the arm arrangement, comprising a procedure wherein the feet of the patient are positioned on a footplate or footrests with the legs below the knees substantially vertical, a sling is passed around the back of the patient underneath the arms thereof and, with said sling attached to said attachment points, said attachment points are moved upwardly along a generally arcuate path relative to the position of the feet which arc has an effective radius comparable to the length of the thigh bones of the patient whereby to raise the latter to a generally standing position on said footplate or footrests whilst otherwise supported and laterally located by the sling, and said arc is centred about a lateral horizontal axis parallel to an imaginary line joining said attachment points and to imaginary lines respectively joining the centres of pivotal movement of the knee and hip joints of the patient, which axis remains fixed relative to said footplate or footrests and is disposed substantially directly above the heel position of the patient with the latter facing said axis."
"4. A method according to any one of the preceding claims, wherein the hoist is initially positioned with the knees of the seated patient located against knee abutment means of the hoist."
"5. A method according to claim 3, wherein the weight of the patient is supported solely by said sling and by the footplate or footrests whilst the patient is being lifted from the seated to the standing position."
"6. A patient hoist comprising an upstanding support structure, a lifting arm arrangement projecting from the support structure and providing laterally spaced attachment points for the attachment of a body support sling positioned around the back of a seated patient below the arms thereof, said attachment points being rigidly located laterally of the arm arrangement which is pivoted about a horizontal axis with the attachment points disposed at a radius comparable to the average length of a human thigh bone, a footplate or footrests on or fixed relatively to the support structure, and a lifting mechanism operative to raise the lifting arm arrangement in such manner that the attachment points thereof move along a generally arcuate path centred on a lateral axis parallel to an imaginary line joining said attachment points, such movement of the lifting arm arrangement being sufficient to raise the patient to a standing position with the feet of the latter supporting a substantial part of the total body weight of the patient while the latter is also supported and laterally located in the standing position by said sling."
"7. A hoist according to claim 6, wherein said lifting arm arrangement is mounted on said support structure for solely pivotal movement about said horizontal axis by said lifting mechanism, and said support structure with said horizontal axis disposed substantially directly above the footplate or footrests."
"10. A hoist according to any one of claims 6 to 9, wherein knee abutment means are mounted on said support structure for location of the knees of the patient."
"11. A patient hoist comprising an upstanding support structure for example a column, a pivotal lifting arm arrangement projecting from one side of the column and providing laterally spaced attachment points for the attachment of a padded body support sling passed around the back of a patient below the arms thereof with the attachment points rigidly located laterally of an arm arrangement which is pivotal about a fixed horizontal axis parallel to an imaginary line joining the attachment points which are disposed at a radius comparable to the average length of a human thigh bone, knee location abutment means on the support structure, a footplate or footrests on or attached to the support structure and a lifting mechanism operative to raise the lifting arm arrangement about said horizontal pivot axis through an angle sufficient to raise the patient, with the knees of the latter located against said abutment means, to a standing position on the footplate or footrests with the feet of the patient supporting a substantial part of the total body weight of the latter whilst supported from behind and laterally located by the sling."
REASONING OF THE TRIAL JUDGE ON CONSTRUCTION AND INFRINGEMENT
Introduction
Questions of construction are at the heart of the case. After noting certain "rules of construction" applicable to patent claims, his Honour turned to the language of claims 6 and 11. He found, on the basis of the evidence of Ms Brown, an occupational therapist called by Impro-Arjo:
" ... that, as at the priority date, 2 June 1983, the available hoists suffered from a number of disadvantages; that fixed hoists were generally used to solve a single lifting problem, usually by employing a sling used to cradle the whole of the patient's body; and that the mobile hoists then used utilised a mast with a spreader bar system" (at 122)
and that:
" ... the hoist of the Patent exemplified in the embodiment called the "Stella" was unusual in that it had a foot platform and a back support, or sling, which supported the patient while being lifted into a semi-standing or standing position; ...." (at 122).
Nesbit's fundamental submission
In relation to claim 6, His Honour said, in an important passage:
"It will have been noted from the above breakdown of this claim that there is nothing, at least explicitly, in its language to suggest that the invention possesses the following two essential features: (1) the "parallelogram" concept, approximate or otherwise; and (2) the absence of horizontal force at the knees. As has been said, it is a rule of construction that it is not permissible to confine the scope of a claim by reference to limitations which may be found in the body of the Specification, unless they are expressly, or by necessary implication, picked up by the claim. In the absence of the express incorporation of these two features into claim 6, the question arises whether either should be read into the claim by implication." (at 123)
This passage derives its significance from Nesbit's fundamental submission that central to the Invention and the claims were certain interrelated essential features of the mechanics by which the lifting of the patient's body takes place. The submission was that according to the claims, there must be a sufficient similarity between the effective length of the lifting arm of the device (the effective length is from the horizontal axis, pivot or fulcrum to the sling attachments, any extension beyond those attachments being irrelevant) and the average length of a human thigh bone; that there must be an approximate parallelogram, the other two sides of which are the straight line between the fulcrum and the centre of the straight line between the patient's knee joints, on the one side, and the straight line between the centre of the straight line between the sling-attachment points and the centre of the straight line between the patient's hip joints on the other side; and, finally, that the lifting process must (a) operate according to a "parallelogram of forces", and (b) not involve any horizontal pressure in a forward direction at the knees. Nesbit submitted that in the case of both the Mark I and Mark II, the lifting arm was much longer than the average length of a human thigh bone; that there was no approximate parallelogram of the kind described; and that the lifting process (a) did not operate according to a parallelogram of forces, and (b) always involved horizontal pressure in a forward direction at the knees.
"Parallelogram" and "parallelogram of forces"
His Honour first addressed the "parallelogram" concept, which featured several times in the body of the Specification but was not referred to in terms in the claims or in the accompanying drawings. He thought that the Specification did not contemplate a dynamic process involving a "parallelogram of forces". Rather, he thought that the word "parallelogram" was used to refer to a "by and large" geometric form. His Honour found that parallelogram lifting action or movement or motion were not terms of art in the field of mechanical engineering, and noted that it was eventually common ground between the experts that "although the four-bar linkage is a basic mechanism in engineering, the notion of the 'parallelogram' is a geometric concept".
His Honour thought that reference to dictionaries supported the proposition that a "parallelogram" was a concept of geometry rather than one of mechanical engineering, and that "its primary orientation is towards a description of the form of that figure rather than a description of a mechanical process". He said:
"... there is nothing in the present context to suggest that 'parallelogram' was not intended to have this ordinary geometric meaning, that is, something which is essentially descriptive of the form of the subject figure." (at 127)
The trial Judge referred to mentions of the expression "parallelogram of forces" in the Oxford and Macquarie dictionaries. In the Oxford English Dictionary (2nd edn, 1989) the expression occurs as part of the following illustrative quotation in the definition of "parallelogram":
"parallelogram of forces (Dynamics): a figure illustrating the theorem that if two forces acting at one point be represented in magnitude and direction by two sides of a [parallelogram], their resultant will be similarly represented by the diagonal drawn from that point; hence, a name for the theorem itself."
The Macquarie Dictionary gives this separate definition of "parallelogram of forces":
"a parallelogram drawn in such a manner that two adjacent sides represent two forces acting on a body, both in magnitude and direction; the diagonal of this parallelogram then represents the resultant of these two forces."
The trial Judge was of the view that it could not be suggested that the Specification contemplated the existence of a particular dynamic process involving a parallelogram of forces or the theorem referred to in these dictionary passages. I agree.
His Honour also considered whether the term "parallelogram", as used in the body of the Specification, was meant to convey a "precise geometric concept" or "no more than a 'by and large' notion". He noted that this issue of construction remained primarily a matter for the Court (he referred to Minnesota Mining and Manufacturing Company v Beiersdorf (Australia) Ltd (1980) 144 CLR 253 at 270, 281 (Aickin J)). He preferred the "by and large" construction, observing in support that there was no express requirement of a precise geometric parallelogram; that there were several references in the body of the Specification to a "more or less" or "approximate" parallelogram; that no valid "functional or mechanical reason" was advanced for a requirement of a precise geometrical figure; and that the drafter must have appreciated, given the obvious variations in the height and stature of patients, that the attainment of a precise parallelogram in every case, or even in most cases, was unlikely to be feasible. Again, I agree with his Honour's conclusion as to the sense in which the word "parallelogram" is used in the Specification.
Is the "approximate" parallelogram to which the Specification referred implied in claim 6? His Honour said:
"In my opinion, when the Specification is read as a whole, it appears clearly enough that it proceeds upon the assumption that the lifting movement, in all its aspects, can be seen as analogous to a parallelogram, or as something approximating a parallelogram. It follows, in my view, that it should be taken as implicit in each of the claims that the lifting movement be so perceived. It must further follow that I would infer the existence of this element in claim 6 as a matter of necessary implication, given the importance of having something like a parallelogram action to assist in providing a desirable constraint on movement and thus contributing to patient comfort in a significant respect." (at 130) (underlining in original)
However, his Honour referred to the construction supported by Nesbit as requiring "a geometrically precise parallelogram". He rejected that construction:
"No logical, technical or mechanical reason was advanced to support the need for such a precise requirement, which has no apparent nexus with the practical objectives of the invention. Those objectives, ..., are in essence, to provide a method of lifting a patient from a sitting position, and to provide hoists for so raising a patient, which largely overcome the disadvantages, previously identified, of prior art methods and hoists; and, as a specific object, to provide such a hoist which is relatively cheap to manufacture, which is of conveniently light and compact form, and which is simple to operate. In short, it was never an objective of the invention to achieve a parallelogram as such, that is, as an end in itself, and certainly not a geometrically precise one.
... in referring to an 'approximate' or 'more-or-less' parallelogram, the draftsman was merely seeking to express, in a practical and illustrative way, the notion that, as the lifting arm is moved through an arc, so too the thigh of the patient is moved through an arc (the knees and hip joints of the patient being the relevant human pivot points); so that the lifting arm and the thigh maintain a co-operative, or sympathetic, motion to bring the patient from a seated position to a substantially standing position; and that this is achieved in part by the use of the sling which is attached to the lifting arm at one of the pivot points of the notional parallelogram, and which provides the means by which force is applied to the patient to bring him or her both upwards and forwards into a substantially standing position." (at 130-132 - emphasis supplied)
His Honour thus held that only an approximation of a parallelogram was intended, "with a view, ... to emphasising the essential feature of the Patent that there is a requirement of a sympathetic motion between the lifting arm and the patient's thighs" (at 146 - emphasis supplied). In favouring the "by and large", "approximate" or "notional" parallelogram concept, the trial Judge referred to the Full Court's statement in Freeman v TJ and FL Pohlner Pty Ltd (1994) 30 IPR 377 at 385, that to resolve a "dilemma of construction", the Court should look to the reaction to the claim of a notional skilled addressee, assuming that he or she would, in accordance with authority, lean to a construction which favoured successful operation. Bearing in mind the expert evidence, his Honour was satisfied that "the notional skilled addressee in the present case would lean to a 'by and large' construction of the parallelogram concept in order to achieve a successful operation of the lifting hoist in accordance with the clear object of the invention" (at 132). He said that he did not accept the opinions of Nesbit's experts in so far as they depended upon a precise geometric interpretation of claims 6 and 11.
Nesbit submits that the learned trial Judge erred in attributing to it
"a case at trial which attributed to the features of the claims of the Patent involving a parallelogram a requirement that there be a precise geometric figure ... which was the antithesis of a 'more-or-less' or 'by and large' parallelogram of forces ... to achieve a mechanical effect".
Nesbit also submits that his Honour erred by failing
"to attribute to the features of the claims involving a parallelogram any limits capable of defining and marking out the boundaries of the invention of the Patent".
I will address these submissions later.
Horizontal forward force or pressure at the knees; presence of a "knee abutment means"
The trial Judge observed that there was no reference in claim 6, in terms at least, to "knee abutment means" on the upright stem or column of the apparatus or to the absence of force at the knees, although both were mentioned in the body of the Specification. He observed, however, that a "knee location abutment means" was mentioned in claim 11 and appeared in Figures 1 and 6 (it also appears in Figure 4).
His Honour referred to statements in the Specification that there was "no horizontal force tending to displace the knees", that the knee abutment means was "for location of the knees" or "engagement with the knees ... during initial positioning of the hoist and during lifting", and that "patients with sufficient muscular strength [would] involuntarily straighten their legs during lifting so that, in the final position the body [would be] completely straight between the footrests ... and the sling ... [and that] for these patients the abutment means ... merely provide location at the initial stage of the lift" (emphasis supplied). After considering dictionary definitions of "abutment", his Honour concluded:
"In my opinion, when taken in its context here, the phrase 'knee abutment means' meant a means, either of locating the knees or of resisting pressure from the knees, depending upon the patient's circumstances. In other words, the phrase is capable of being applied in several different situations and is thus capable of application whether or not there is pressure or force to be resisted. This construction is consistent with the ordinary meanings of 'abutment'. It is also in accordance with the explanation of the working of the invention given in the body of the Specification, that is to say, that in the case of severely disabled patients, the knee abutment means will serve to resist pressure from the knees so that the knees are not displaced; but in the case of patients with sufficient musculature in the legs, the more vertical the lift, the less the horizontal pressure from the knees and, in an ideal situation, to maximise patient comfort, there will be no such pressure; so that the only function of the knee abutment means in that situation is to provide a point of location, or engagement of the knees." (at 136-137)
His Honour went on to address the question whether a knee abutment means, having the dual function mentioned in this passage, should be implied in claim 6. He reached the conclusion, challenged by Nesbit on the appeal, that it should be. His reasons for reaching this conclusion are found in the following passage:
"In my opinion, reading the Specification as a whole such a feature should be treated as if incorporated in claim 6, unless one can construe claim 6 as limited to those patients with sufficient musculature in the legs to be able to involuntarily straighten the legs during the lift so that the body, in the final position is completely straight. In my view, there is no reason, logical or technical or otherwise, to read down the claim in this way. The more logical interpretation, given the context, namely an objective of providing a hoist to assist invalids, would be to construe the claim so that it was capable of application to, although not limited to, severely disabled patients. That is to say, given an assumption, which is properly to be made, that the hoist was intended for use, to a significant extent, by severely disabled patients, it must follow that in those cases at least some horizontal force will be created. It follows, I think, that the knee abutment means must be regarded as a necessary element of claim 6. Even in an 'ideal' situation, such means are still necessary to locate or engage the knees to that extent in any event. That is to say, the incorporation of these means is necessary in order that the invention claimed in Figure 6 may work. In my opinion, this feature, that is, the knee abutment means having the dual possible function already mentioned, is implicit in claim 6. However, for the reasons already given, I cannot accept that it is implicit in this claim that in every application of the hoist there must be no horizontal force at the knees." (at 137-138) (emphasis supplied)
His Honour thought that this reasoning also applied to claim 11 in which, in any event, a knee abutment means was expressly mentioned. He said:
"It follows that I accept the submission by counsel for Impro and Arjo that the affidavit evidence in chief of the experts called by Nesbit proceeded upon an assumption made of an 'idealised' form or version of the actual invention. Insofar as that evidence depended upon an assumed interpretation of the Patent that required both a strict geometric parallelogram and an entire absence of horizontal force at the knees in every application of the apparatus, I do not accept that construction and, accordingly, cannot accept such evidence." (at 139)
Importantly, his Honour pointed out that although Nesbit's argument proceeded on the assumption that a perfect parallelogram would result in an absence of horizontal force at the knees, this assumption could not be made in the absence of an additional assumption, namely, that the horizontal axis of the lifting arm and the patient's knees and heels were all in the same vertical plane. However, he noted that claims 6 and 11 were silent as to the location of the horizontal axis. He considered, further, that the provision for knee abutment means in the body of the Specification, in the Figures and in claim 11, all showed that it was contemplated that in some embodiments there would be some force at the knees, and, finally, that the angle of the sling would itself provide a horizontal component to the lifting force which would itself result in some lateral force at the knees (at 147-8).
Nesbit submits that the width of his Honour's construction of the expression "radius comparable to the average length of a human thigh bone" (see below) and his erroneous construction of the features of the claims involving a parallelogram (see above) obliged him to imply (impermissibly) an essential feature (knee abutment means) in claim 6 which is present only in later claims, such as claim 11. Nesbit submits:
"His Honour's reasoning in effect compelled his Honour to do this so as to permit substantial horizontal force at the knees during the lifting action, which would not take place with a parallelogram lifting motion involving a parallelogram of forces.
It is impermissible (and, with respect, wholly novel) to imply an essential feature in a claim, and, further, his Honour's conclusion was contrary to well established principles of construction and contrary to the evidence."
"Comparable to the average length of a human thigh bone"
His Honour set out the relevant occurrences of this expression in the body of the Specification and in claims 6 and 11 (see above). He then noted the division between the experts in relation to the significance of the terms "comparable" and "average", referred to dictionary definitions of these terms, and concluded that the composite phrase signified,
"... capable of ... being represented as similar or analogous, or of being likened to"
"the ruling or typical case or the common run"
of the length of the human thigh bone.
In the learned trial Judge's view, the expression, so construed, was to be given effect according to a "by and large" rather than a mathematical approach. His Honour held that the requisite comparison was not an abstract one "where the addressee of the Patent is merely called upon to ascertain whether or not the length of the relevant radius falls within a notional range of measurement" (at 149). Rather, his Honour preferred the view that:
"... a common sense approach to construction should be adopted which has regard to the facts that what is claimed to be a feature is a radius identified by reference to a lifting hoist designed to lift a patient from a seated to a substantially standing position by means of a sling attachment to a lifting arm arrangement; and that, in the operation of the invention, as the lifting arm pivots and moves from a rather horizontal disposition to a more vertical one, so also the patient's thighs pivot at the knee and at the hip, and also move from a rather horizontal disposition to a more vertical one, and at all times the thighs move in co-operation, or in sympathy with, the lifting arm. Further, ..., in this connection, the issue of 'comparability', which necessarily involves an element of judgment, is to be tested by reference to this functional characteristic." (at 149-150)
His Honour rejected what he characterised as the "strict approach" which he found to be suggested by Nesbit's expert evidence (in which an attempt was made to assign to the length of the radius a precise range of measurements based on anthropometric data not referred to in the claims or in the body of the Specification), as leading to fine, artificial, and, in some cases, arbitrary distinctions. As the device in question was one for lifting rather than measuring, he considered such a strict approach to be "inconsistent with the whole tenor of the Patent" (at 152).
Nesbit submits that his Honour erred by choosing a meaning which was not open on unchallenged evidence and which "rendered the feature meaningless and incapable of defining and delimiting the invention of the Patent".
Particular submissions by Nesbit
His Honour addressed certain further particular submissions made by Nesbit. It seems fair to generalise, however, that his rejection of them arose from his conclusions on the more general issues discussed above, in particular, on his broad "by and large" construction of the expressions "parallelogram" and "comparable to the average length of a human thigh bone", and his rejection of Nesbit's submissions as founded upon a too "strict", "precise" or "geometric" construction.
Conclusion on infringement
The learned trial Judge concluded that both of Nesbit's Mark I and Mark II products infringed claims 6 and 11 construed in the broad purposive manner described above.
THE PARTIES' SUBMISSIONS ON THE APPEAL RELATING TO CONSTRUCTION AND INFRINGEMENT
Grounds of appeal
The grounds of appeal relied on by Nesbit against his Honour's conclusion that it had infringed claims 6 and 11, are perhaps sufficiently indicated by the issues, to which I have already referred, on which the trial Judge decided against it. In particular, Nesbit asserts that the trial Judge erred in failing to give any meaning, or any sufficiently definite meaning, to the features of claims 6 and 11 and the claims dependent on them,
"requiring the lifting motion to be achieved by an action defined by, inter alia:
(a) the average length of the human thigh bone; and
(b) matching substantially opposite sides of a parallelogram by an adjustable lifting arm or a lifting arm approximately equal to the average length of a human thigh bone"
and in implying into claim 6 a requirement that there be a knee abutment means with the dual functions mentioned earlier.
Outline of Nesbit's submissions on the appeal on construction and infringement
Nesbit's written submissions on the appeal comprise 63 paragraphs, some containing numerous subparagraphs and lengthy footnotes. In relation to infringement, Nesbit submits, in outline, as follows:
In relation to the parallelogram issue, the trial Judge's construction fails to define the Invention and is contrary to its objects and description as set out in the Specification . In particular, his Honour's conclusion that no "functional or mechanical reason has been advanced to require that there be a precise figure in order that the invention may work" did not have regard to the object of replication of the nurses' lift. The trial Judge erred in accepting that a "by and large" parallelogram is one which "essentially, has no defined parameters". The fact that the combination of human and machine parts makes a perfect parallelogram unattainable, so that it is referred to in the embodiments in the Specification as a "more-or-less" or "approximate" parallelogram lifting action is not to the point. Nesbit's devices do not exhibit an apparent parallelogram lifting motion.
The trial Judge impermissibly based his conclusion on definitions of "parallelogram of forces" which were not put to the expert witnesses and were not the subject of evidence or submissions. Further, he failed to take account of uncontradicted evidence that the requirement of a parallelogram was to be construed as including a dynamic process involving a parallelogram of forces.
The trial Judge wrongly attributed to Nesbit a case at trial requiring a precise geometric figure.
The trial Judge's construction of the phrase "radius comparable to the average length of a human thigh bone" rendered it meaningless and incapable of defining and delimiting the Invention. He accepted a construction which was not open on the evidence. He erred in rejecting, or failing to accept, and in not paying proper regard to, the evidence of Mr E R Scull, Bioengineer, Department of Medical Physics, Royal Perth Hospital, called by Nesbit, the witness best qualified as the notional addressee. His Honour failed to give an explanation for disregarding the anthropometrical evidence of Mr Scull and Dr T R Ackland, Senior Lecturer, Department of Human Movement, University of Western Australia, also called by Nesbit.
His Honour's reasoning on the "thigh bone" and "parallelogram" issues compelled the implication of a knee abutment means as an essential feature of claim 6 "so as to permit substantial horizontal force at the knees during the lifting action, which would not take place with a parallelogram lifting motion involving a parallelogram of forces". It is impermissible, to imply an essential feature into a claim. The knee abutment means referred to in claim 11 is only an inessential feature of that claim. In the claimed Invention, the knee abutment means is "for the limited and specific purpose of location of the knees of the patient upon initial engagement and thereafter for the knees to remain at rest against the knee abutment means without being subjected to any or any substantial horizontal force tending to displace same". Further, there is absent from the parallelogram lifting action in the claimed Invention any horizontal force tending to displace the knees. Yet on Nesbit's devices, the knee abutment means is "for the specific purpose of being subjected to and restraining the substantial horizontal force which is generated by the knees as a result of the dynamic mechanical process involved in the lifting action".
Nesbit's Easi-Stand devices differ substantially from the essential features of the Invention, in that the pivot of the lifting arm arrangement is not disposed substantially directly above the patient's heel and there is substantial horizontal force at the patient's knees.
Outline of Impro-Arjo's submissions on the appeal on construction and infringement
Impro-Arjo's submissions comprise 57 paragraphs and a further 8 paragraphs of supplementary submissions. In outline, their submissions on infringement are as follows:
The Specification uses the "analogy" of a parallelogram, with the emphasis on its upper and lower limbs, to describe the lifting motion. The drafter was not seeking to prescribe a necessity of geometric precision. This is made clear by the use of expressions such as "approximates to a more-or-less parallelogram motion". The drafter was simply trying to express, in a practical and illustrative manner, the idea that, as the lifting arm moves through an arc, the patient's thighs move through an arc also, so that the lifting arm and the thighs maintain a cooperative and sympathetic motion to bring the patient from a seated position to a substantially standing position.
The Invention was not to provide a lifting motion dependent on geometric precision, and an absence of force tending to displace the knees. Regardless of whether there is a perfect parallelogram, horizontal force will exist at the knees when the pivot is not in the same vertical plane as the patient's heels, or when the sling is at an angle. Both the Specification and the claims accept that in the operation of the Invention there will be force at the knees, and they include a knee abutment means to resist it and prevent displacement of the knees.
Nesbit's construction of the relevant claims is unduly restrictive in requiring the lifting mechanism to conform to a geometric parallelogram (at worst within very small and precise tolerances), and in limiting the operation of the hoist by reference to the result that there be no horizontal force tending to displace the knees. But the claims are not so limited. Nesbit's evidence in chief assumes an "idealised" form of the Invention rather than that disclosed in the Patent. Nesbit seeks to distinguish between hoists where there will always be a force at the knees (its Easi-Stand hoists), and hoists where there may or may not be (the Patent hoists). However, the latter include the former embodiments, as there is no difference in substance between them.
Nesbit accepts that its Easi-Stand hoists possess the integers of claims 6 and 11 except:
"[A lifting arm arrangement]...with the attachment points disposed at a radius comparable to the average length of a human thigh bone".
Impro-Arjo's witnesses found all the integers of claims 6 and 11 to be in both Easi-Stand hoists. Hence the single issue for determination on infringement was whether the arc of the radius of the lifting arm in Nesbit's devices is "comparable to the average length of a human thigh bone", a question related to the notion that the lifting motion can be described as an approximate parallelogram.
The comparison is not an abstract one, involving ascertaining whether or not the length of the radius falls within a specified range of measurements. That approach is extremely artificial and is not suggested by the Specification. The common sense approach is to have regard to the fact that what is claimed is a feature of a hoist designed to lift a patient from a seated to a substantially standing position by means of a sling attached to a lifting arm arrangement. The comparison will necessarily involve questions of judgment, but regard should be had to the functional context. So construed, "comparable" means that the radius must be of a length such that the movement of the lifting arm arrangement through an arc is sufficient to raise the patient from a seated to a substantially standing position.
The location of the pivot point is not specified in claims 6 and 11. Where it is not substantially directly above the patient's heels but is further forward, the radius must be of a length which is sufficient to lift the patient, and if it does so, it can be seen to be "comparable to the average length of a human thigh bone". The words "average length of a human thigh bone" remind the notional addressee that the hoist is to have universal application for all patients (male and female, tall and short, heavy and light, and regardless of race). There was no evidence as to a reason for the differing radius lengths as between the Easi-Stand Marks I and II and Nesbit's expert witnesses accepted that there was no real difference in function between them.
There is no difference in function between the hoists of the Patent and the two Easi-Stand hoists, regardless of the fact that the Easi-Stand hoists always require knee abutment means. It was not suggested by Nesbit's witnesses that its hoists provided any advantage or improvement over that described in the Specification.
Impro-Arjo's approach to construction is preferable because it does not depend on arbitrarily determined ranges of lengths which do not appear in the Specification and because it is a common sense practical approach.
Nesbit's submissions are also based on the fundamental misconception that a parallelogram lifting motion, of itself, necessarily results in the absence of force at the knees. It was established in cross-examination that even if there is a perfect parallelogram, there may be horizontal force at the knees. A parallelogram motion without horizontal force at the knees requires the imposition of the additional requirement that the pivot point and the patient's knees and heels be in the same vertical plane. The requirement of claims 1 to 5, that the axis of the pivot of the lifting arm be "disposed substantially directly above the heel position of the patient..." does not appear as a limitation in claim 6 or 11. It must be accepted, as Nesbit's witnesses accepted, that the Patent encompasses embodiments which do not contain this feature. Claims 6 and 11 say nothing about the location of the pivot point, whereas other dependent, and hence more limited, claims (eg claim 7) specify the feature. This demonstrates the broader scope of claims 6 and 11. There is no claim dependent on claim 11 which introduces the feature that the pivot point of the lifting arm is disposed substantially directly above the patient's heels; the provision for knee abutment means recognises that some embodiments will involve force at the knees.
REASONING ON THE APPEAL RELATING TO CONSTRUCTION AND INFRINGEMENT
General Principles of Construction
The issue of the correct approach to the construction of patent claims has often been discussed. In Decor Corporation Pty Ltd v Dart Industries Inc (1988) 13 IPR 385 (FCA/FC), Sheppard J distilled ten "rules of construction" (at 400):
"(1) The claims define the invention which is the subject of the patent. These must be construed according to their terms upon ordinary principles. Any purely verbal or grammatical question that can be answered according to ordinary rules for the construction of written documents is to be resolved accordingly.
(2) It is not legitimate to confine the scope of the claims by reference to limitations which may be found in the body of the specification but are not expressly or by proper inference reproduced in the claims themselves. To put it another way, it is not legitimate to narrow or expand the boundaries of monopoly as fixed by the words of a claim by adding to those words glosses drawn from other parts of the specification.
(3) Nevertheless, in approaching the task of construction, one must read the specification as a whole.
(4) In some cases the meaning of the words used in the claims may be qualified or defined by what is said in the body of the specification.
(5) If a claim be clear, it is not to be made obscure because obscurities can be found in particular sentences in other parts of the document. But if an expression is not clear or is ambiguous, it is permissible to resort to the body of the specification to define or clarify the meaning of words used in the claim.
(6) A patent specification should be given a purposive construction rather than a purely literal one.
(7) In construing the specification, the court is not construing a written instrument operating inter partes, but a public instrument which must define a monopoly in such a way that it is not reasonably capable of being misunderstood.
(8) The body, apart from the preamble, is there to instruct those skilled in the art concerned in the carrying out of the invention; provided it is comprehensible to, and does not mislead, a skilled reader, the language used is seldom of importance.
(9) Nevertheless, the claims, since they define the monopoly, will be scrutinised with as much care as is used in construing other documents defining a legal right.
(10) If it is impossible to ascertain what the invention is from a fair reading of the specification as a whole, it will be invalid. But the specification must be construed in the light of the common knowledge in the art before the priority date."(emphasis supplied)
There is a danger in considering the integers of a claim individually and in isolation: the approach can easily yield a literal rather than a purposive construction. In Catnic Components Ltd v Hill & Smith Ltd [1982] RPC 183 ("Catnic Components")Lord Diplock said, in an oft-cited passage (at 243):
"A patent specification should be given a purposive construction rather than a purely literal one derived from applying to it the kind of meticulous verbal analysis in which lawyers are too often tempted by their training to indulge. The question in each case is: whether persons with practical knowledge and experience of the kind of work in which the invention was intended to be used, would understand that strict compliance with a particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention so that any variant would fall outside the monopoly claimed, even though it could have no material effect upon the way the invention worked."
The comments of Dixon J in Radiation Ltd v Galliers & Klaerr Pty Ltd (1938) 60 CLR 36 (at 51) are also pertinent:
"But, on a question of infringement, the issue is not whether the words of the claim can be applied with verbal accuracy or felicity to the article or device alleged to infringe. It is whether the substantial idea disclosed by the specification and made the subject of a definite claim has been taken and embodied in the infringing thing."
These authorities have been understood as directing the court to "[avoid] too technical or narrow a construction of claims" (see Winner v Morey Haigh & Associates (A'asia) Pty Ltd (1996) 33 IPR 215 (FCA/O'Loughlin J)at 221; Populin v HB Nominees Pty Ltd (1982) 41 ALR 471 (FCA/FC) at 475).
In Improver Corp v Remington Consumer Products Ltd [1990] FSR 181 ("Improver") (at 189), Hoffman J identified three questions posed for a court by Lord Diplock in Catnic Components:
"(1) Does the variant have a material effect upon the way the invention works? If yes, the variant is outside the claim. If no-
(2) Would this (i.e. that the variant had no material effect) have been obvious at the date of publication of the patent to a reader skilled in the art. If no, the variant is outside the claim. If yes-
(3) Would the reader skilled in the art nevertheless have understood from the language of the claim that the patentee intended that strict compliance with the primary meaning was an essential requirement of the invention [?] If yes, the variant is outside the claim.
On the other hand, a negative answer to the last question would lead to the conclusion that the patentee was intending the word or phrase to have not a literal but a figurative meaning (the figure being a form of synechdoche or metonymy) denoting a class of things which included the variant and the literal meaning, the latter being perhaps the most perfect, best-known or striking example of the class."
In Kastner v Rizla Ltd [1995] RPC 585, the English Court of Appeal approved the purposive approach to construction enunciated by Lord Diplock in Catnic Components, and the three questions intended to give effect to it formulated by Hoffman J in Improver.
Another relevant "rule of construction" is that it is not permissible to confine the scope of a claim by reference to limitations found in the body of the Specification, unless they are expressly or by necessary implication picked up in the claim: Martin v Scribal Pty Ltd (1954) 92 CLR 17 at 97 (Taylor J) (affirmed at 95 CLR 213 (PC)); Glaverbel SA v British Coal Corp [1994] RPC 443 (Mummery J) at 485-6; Sartas No 1 Pty Ltd v Koukourou & Partners Pty Ltd (1994) 30 IPR 479 (FCA/Gummow J) at 485-6. Where an expression in a claim is unclear, however, resort may be had to the body of the Specification to ascertain its meaning: Interlego AG v Toltoys Pty Ltd (1973) 130 CLR 461 at 478-9.
A further principle is that a construction according to which the invention will work is to be preferred to one according to which it may not do so (see, for example, Martin v Scribal Pty Ltd, supra, at 97; Welch Perrin & Co Pty Ltd v Worrel (1961) 106 CLR 588 at 601-2, (Menzies J); Freeman v TJ and FL Pohlner Pty Ltd, supra, at 381).
On the hearing, at trial and on the appeal, there was no dispute over these principles of construction. What has been in contention is their application to the facts.
Purpose of the Invention
The objects of the Invention were set out earlier and will not be repeated here. In my view, the claims must be construed in the light of the Invention's purpose of providing a substitute, "of conveniently light and compact form" for a nurses' lift to a generally standing position, for "infirm and disabled persons generally." This consideration draws attention to the fact that "the nurses' lift" is a concept of surely infinite variety, according to the stature, weight and strength of the patient on the one hand, and those characteristics as well as the work methods of the particular nurses concerned on the other hand.
On 21 April 1997, that is to say, subsequent to the trial and shortly before the hearing of the appeal, Jacob J decided an appeal (from a decision of the Patent Office dated 7 November 1996) in the Chancery Division (Patents Court) of the High Court of Justice in relation to the same patent in Great Britain. The case was Re Patent GB 2 140 773 in the name of Impro Ltd; ex parte The Helping Hand Company (Ledbury) Ltd. The Hearing Officer had made a declaration of non-infringement from which Impro appealed. With respect, in the present context I find persuasive and acceptable what Jacob J said in the following passage:
"This patent, I think, should be approached from its essential purpose to start off with, which is to emulate what the nurses do. No one would suggest that a team of two nurses lifting a patient always lifts the patient in precisely the same way. Doubtless the feet stay on the ground. Doubtless the knees stay, roughly speaking, in the same position. But whether the patient is pulled slightly more forward or slightly more upwardly at first is not generally material to the operation. The path followed by the patient as he or she has lifted is a generally arcuate path if one thinks of the patient's shoulders, and it is that path which really matters. It is not a precise path and so when the skilled man comes to read the bit about the arc having an effective radius, I think he will be considering what is effective in practice to get the patient from sitting to vertical and when he sees the bit about comparable to the length of the thigh bones of the patient, he will not be thinking of mathematical comparison, but he will be thinking of comparable for what purpose. It is for the purpose of getting the patient up. I think he will read this passage very loosely, bearing in mind the inventor's purpose." (at 5-6)
It could hardly be suggested that a nurses' lift never involves any forward movement of the patient's knees. No doubt the extent of forward movement varies from "nil" to "substantial". The movement of the thigh bone will always involve some element of an arc but the arc will vary greatly from one nurses' lift to another. That variety will be a function, not only of the length of the thigh bone, but also of any forward movement of the knees and of the extent of "uprightness" ultimately attained. The musculature of the patient and the specific objectives and practices of the particular nurses effecting the lift will also play a role.
Claims 6 and 11 should not be construed to exclude some particular forms of nurses' lifts if they can be fairly construed so as to encompass them.
"Parallelogram" and "parallelogram of forces"
I said earlier that I agreed with the trial Judge's conclusion that the Specification did not contemplate a dynamic process involving a parallelogram of forces or its theorem. There is no reference to a "parallelogram of forces" in claim 6 or 11. Nor do they import it by implication. There is nothing in the claims, the Specification or the evidence to suggest that any two adjacent sides of the "parallelogram" represent or coincide with particular directional forces and there is no reference in any of them to magnitude of forces. The "uncontradicted evidence" on which Nesbit relies to support its submission does not do so.
Nesbit submits that the trial Judge reached his conclusion on the present issue in a manner not allowable, because he referred to "various [dictionary] definitions of a mechanical parallelogram of forces which were not put to any of the expert witnesses and were not the subject of any evidence or submission from either party." Let so much be assumed in favour of Nesbit. "Parallelogram of forces" (as defined) on the one hand must be distinguished from "parallelogram" and "parallelogram lifting action" on the other. The fact is that a particular dynamic process ("parallelogram of forces"), as distinct from a very approximate geometric shape ("parallelogram" and "parallelogram lifting action"), is clearly not implied in the claims.
Despite the consensus of the experts that a parallelogram lifting action is a feature of claims 6 and 11, the question raised is ultimately one of construction for the Court. A "parallelogram" is not referred to in these claims, or in the accompanying drawings. The question is whether this feature is implied in either claim. That the parallelogram in question, if implied, is an "approximate", "by and large" or "more-or-less" one, was common ground on the appeal.
Nesbit resisted the notion that the supposed implication depended only on the meaning of the phrase "comparable to the average length of a human thigh bone". Nesbit also relied on an absence of horizontal force at the knees and the omission of any reference to a knee abutment means in claim 6 as necessarily implying a parallelogram lifting action. It will be recalled that both claims 6 and 11 are silent as to horizontal force at the knees and that claim 11 does, while claim 6 does not, mention "knee location abutment means".
Even if absence of horizontal force at the knees were otherwise to be implied, I accept Impro-Arjo's submission that its absence ultimately depends on the satisfaction of conditions in addition to a parallelogram lifting action. A parallelogram lifting action is consistent with the presence of horizontal force at the knees where there is not an appropriately vertical alignment between the patient's heels and knees and the fulcrum of the lifting arm.
It is important to understand that claims 6 and 11 are apparatus claims which deliberately refrain from insisting upon such vertical alignment. The non-insistence on the heels, knees and horizontal axis being in the same vertical plane in those claims stands in contrast to the insistence on it in method claim 1. Method claim 1 reflects the first consistory statement in the body of the Specification while apparatus claims 6 and 11 reflect the second and third consistory statements in the body of the Specification respectively. The first consistory statement and claim 1 refer to a method of invalid lifting. They refer to "a procedure wherein the feet of the patient are positioned on a footplate or footrests with the legs below the knees substantially vertical" and they require that the axis be "disposed substantially directly above the heel position of the patient". Importantly, they describe an "ideal" system which maximises patient comfort by minimising forward horizontal force at the knees and pressure on the body of the sling. These elements are found in the following parts of the first consistory statement:
"The knees of the patient may [not must] initially be located against knee abutment means of the hoist."
"The result is that the lifting is performed with no horizontal force tending to displace the knees. Preferably [not necessarily]knee abutment means are mounted on the support structure so that the knees are not displaced but can remain at rest against the knee abutment means, the lower legs remain vertical thus ensuring that their own weight and half the thigh weight is supported by the feet on the footplate or footrests and there is no transference of this weight to be taken by the sling. This is an important feature contributing to patient comfort as it minimises the pressure on the body of the sling in lifting the balance, which may be approximately 60%, of the body weight." (emphasis supplied)
A knee abutment means is introduced as an integer in dependent method claim 4 and the bearing of substantial weight by the sling is introduced in dependent method claim 5.
The second and third consistory statements and respectively corresponding apparatus claims 6 and 11 are different. They describe the apparatus of a patient hoist. Apparatus claim 6 does not refer to either the position of the knees or the horizontal axis and refers, relevantly, only to "a footplate or footrests on or fixed relatively to the support structure." Its express terms are consistent with a forward location of the horizontal axis and absence of knee abutment means. Dependent apparatus claim 7 adds the feature of verticality by referring to a "horizontal axis disposed substantially directly above the footplate or footrests." Dependent apparatus claim 10 adds the feature of "knee abutment means ... mounted on [the] support structure for location of the knees of the patient." With respect, it seems to me that this makes it clear that neither is an essential integer of independent apparatus claim 6.
The third consistory statement and independent apparatus claim 11 expressly locate the knees against abutment means on the support structure and refer to the patient's "standing position on the footplate or footrests", implying that the lower leg is approximately vertical, but leaving at large the position of the horizontal axis. So long as the horizontal axis can be further forward than the knees and this is not compensated for in some other way, the hips and upper body can be "pulled forward" with the result that the knees can move forward also.
In my view, an approximate parallelogram lifting action is implied in claims 6 and 11, but only in the broadest sense with emphasis on the fact that there is generally cooperative and sympathetic arcuate movement as between the lifting arm and the femur. Several considerations tell against anything more precise. Claims 6 and 11 do not fix the location of the horizontal axis, the length of the sling, or, except in the limited manner to be explained, the effective length of the lifting arm. If the "ideal" lifting method of claim 1 is to be achieved, the horizontal axis will be located substantially directly above the patient's heels, that is to say, the patient's heels and knees will be in the same approximately vertical plane (cf dependent apparatus claim 7). But neither claim 6 nor claim 11 requires an apparatus so built and the horizontal axis may be substantially out of that alignment. The lifting arm and the femur are not required to be parallel. At the outset, the femur will be approximately parallel with the floor. The lifting arm may or may not be. Again, the distance between the horizontal axis and the patient's knees is not fixed: it may be more or less than the distance between the sling attachment points and the hip joints. But in all cases the sling attachment points and the hip joints will move sympathetically in an arcuate path upwards, with intervening straight lines between the horizontal axis and the patient's knees on the one hand and between the sling attachment points and the hip joints on the other. To this limited extent only, a parallelogram lifting action is implied in the claims.
"Radius comparable to the average length of a human thigh bone"
There was evidence before the trial Judge directed to establishing the effective lengths of the lifting arm of the Easi-Stand Mark I and Mark II models and "the average length of a human thigh bone". The former were simple matters of measurement. They were 580 mm and approximately 660 mm respectively. The expert witnesses gave their evidence generally by reference to the length of 580 mm and there was uncontradicted expert evidence that the additional 80 mm made for no difference in the operation of the two models. The evidence did not explain why the arm of the Mark II was longer or why, as was the case, the horizontal axis of the Mark II was further forward than that of the Mark I. One can only speculate that the two features were intended to compensate for each other. It was not suggested by Nesbit's witnesses that either of its hoists provided any advantage or improvement over that which Nesbit contended was described in the Specification.
In relation to the expression "the average length of a human thigh bone", Nesbit and Impro-Arjo disagreed as to whether recourse to a precise measurement or range of measurements was necessary. Nesbit espoused the view that it was. Difficulties inhere in this approach, some of which are obvious. If the expression is taken to signify the "mathematical mean" (one of three dictionary definitions identified by the trial Judge) it calls for an adding up of the lengths of the thigh bones of all humans of all races and ages alive at a moment of time and division of the result by the number of thigh bones measured. Clearly, this task cannot be performed and cannot have been intended. Even if the expression signifies a "medial estimate" (the second dictionary definition identified by his Honour), the evidence shows that the data available does not extend to refer to the whole human race. Among Nesbit's own experts, there was disagreement over the measurement or range of measurements to which recourse should be had, and as to how the "average" was to be calculated. They referred to population census and survey data obtained in the 1970's and 1980's, relating to British Caucasian and Japanese adults only. But Dr Ackland's evidence was that significant differences and variations in data occur as between racial groups.
The trial Judge preferred a third dictionary meaning, "the ruling or typical case or the common run." So do I.
Two sets of data were referred to. They were called the "Pheasant" data and the "Dreyfus" data, after the names of their respective compilers. None of Nesbit's experts calculated the average then allowed a degree of latitude arrived at by reference to functional considerations. Rather, they took as their starting point the percentile range for which equipment of the present kind is usually designed.
There appeared to be significant disagreement as to what measurements were acceptable as being "comparable" to the particular set of data, although it was generally accepted that the notion of comparability is not a term of art. For example, Dr Ackland said that a thigh length of 525 mm is "certainly close" to the 580 mm length of the radius of the Easi-Stand Mark I. In the course of a demonstration of Nesbit's product, Professor Svensson used the shorter of the sling attachments, commenting that the difference in the lengths of the sling of about 50 mm was "only ... small". However, at another point, using Dr Ackland's figures of 95th percentile lengths, Professor Svensson was of the view that 580 mm was 10 per cent over the male 95th percentile, and did not reasonably fall within the range of measurements indicated by the expression "comparable to the average length of a human thigh bone." Professor Svensson was of the view that the notion of comparability signified "within the 5th and 95th percentile limits" because of accepted practice in ergonomic design. However, he also accepted that the Easi-Stand devices would lift a person with a femur length beyond the 95th percentile limits.
Mr Scull proceeded upon the basis that design for 95 per cent of the overall population is common practice for this type of equipment, in accordance with good design principles, giving, on the basis of the Dreyfus data, a range of thigh bone lengths from 350.5 mm (2.5 percentile females) up to 515.6 mm (97.5 percentile males). In his view, a permissible tolerance in the difference between the relevant radius of the lifting arm and the length of the patient's thigh bone was approximately 50 mm. He stated that in respect of this type of equipment, incremental adjustments are usually in the order of 25 mm. He also said that there is some inaccuracy in measuring the length of a femur extending to a maximum error of 39 mm. Mr Scull interpreted the Specification to teach that the arm length is to be adjustable to within 12.5 mm of the measured length of the thigh of the actual patient. But in his opinion it was more likely that the accuracy of measurement would be within a range determined by the overall standard deviation of the data collated by a number of operators of varying training and skill, in which case the skilled addressee would expect the arm length to be within 42.8 mm of the actual length of the patient's thigh bone. In his view, 580 mm was significantly greater than the range of measurements of femur lengths previously mentioned and exceeded the upper limit (516.6 mm) by 63.4 mm (an excess which is less, it will be noted, than the difference between the effective lifting arms of the Easi-Stand Mark I and Mark II models).
There was some disagreement between Nesbit's experts as to the meaning of "average" in the present context. According to Dr Cheng, Dr Ackland's evidence does not indicate the average lengths of British male and female thigh bones. Dr Ackland presents the 50th percentile value of these two groups. If the distributions were not skewed or multi-nodal then the 50th percentile and the average would be the same. On the assumption of an average of approximately 450 mm, he was of the view that this was not "comparable" to 580 mm.
To Professor Svensson, the word "average" suggested a range of measurements, based on the lengths of the thigh bones of patients likely to use the equipment, rather than those of an "average" patient. In other words, the length of the lifting arm is to be within a range of lengths of thigh bones commonly found in the population for which the hoist is designed.
While I have not found the present issue easy to resolve, I have come to the same conclusion as that reached by the trial Judge, and, subsequently, by Jacob J. Several considerations, some of them related, persuade me to this view. The first is the object of the Invention. The nurses' lift, which the Invention is designed to replace, is a dynamic process involving interaction of the bodies of the patient and the nurses. As noted earlier, the physics and mechanics involved can be expected to be of immeasurable variety. There is no reason to think that the apparatus was intended to provide an effective substitute only in a case where measurement of the effective lifting arm happened to be approximately equal to the average length of a human thigh bone. If possible, claims 6 and 11 should be construed so that the particular integer with which we are concerned does not exclude an effective device.
Secondly, neither claim 6 nor claim 11 fixes a location (either vertical or lateral) for the horizontal axis, or a length of sling. Yet in the dynamics involved, there is inevitably an interrelationship between the location of the horizontal axis, the length of lifting arm and the length of sling. Therefore, considerable latitude must have been intended as to the length of the lifting arm. To put the matter rhetorically, what purpose would be served by constraining the length of the lifting arm while the location of the horizontal axis and the length of the sling are left at large?
Thirdly, it is clear that the Specification does not contemplate grotesquely proportioned hoists with lifting arms many times longer than any particular patient's thigh bone, since one object of the Invention, stated in the Specification, is to provide a hoist of "compact form", which in some embodiments, is mobile and, in some embodiments, is able to be mounted in a toilet cubicle.
Fourthly, it is unlikely that the claims were intended to be limited by reference to the available anthropometric data external to the Specification which, as the evidence in the present case shows, do not speak with one voice, and are racially limited.
Fifthly, it is not suggested that one or other of the Easi-Stand Mark I and Mark II models does not work, or that those two models differ functionally, yet there is a difference of 80 mm between the effective lengths of their respective lifting arms. According to most of the evidence of Nesbit's experts, 80 mm is greater than the difference between the length of the lifting arm of the Easi-Stand Mark I and the "average length of a human thigh bone".
Before I conclude the discussion of the present issue, it is useful to refer to the recent Reasons for Decision of the Hearing Officer and of Jacob J in the English High Court, in Re Patent GB 2 140 773 in the name of Impro Ltd; ex parte The Helping Hand Co (Ledbury) Ltd, unreported. That case involved construction of a patent, the claims of which were in terms substantially identical to the claims in the present case. Claim 6, in both patents, is expressed in terms identical in material respects. In that case, the arm of the lifting arm of the allegedly infringing device was 735 mm in length. It was accepted that the evidence disclosed the average length of a thigh bone to be 407.5 mm, and the maximum length of the thigh bone of a male to be 465 mm. As noted earlier, the applicants were seeking a declaration of non-infringement on the basis that the radius of the lifting arm of their device was "not comparable to the length of the thigh bones of the patient", being "about 80% more than the average" (Jacob J at 5). The applicants argued that the claim was limited to a case "where the radius of the generally arcuate path is approximately the same as the length of the thigh bones of the patient" (Jacob J at 5).
The Hearing Officer applied the three questions formulated by Hoffman J in the Improver case noted earlier. In answer to the first question, he was of the opinion that the longer radius of the lifting arm of the applicants' device had no material effect upon the way in which the device worked. Both versions worked in exactly the same manner, except that the arc of movement of the attachment points had a longer radius. The same can be said in the present case. In this respect, it is important to recall the difference between method claim 1 and apparatus claims 6 and 11 referred to earlier. Absence of horizontal force at the knees is a feature of the method claim (because of its insistence on the feature of verticality) but not of the apparatus claims.
In answer to the second question, the Hearing Officer considered that there was little doubt that at the date of publication, the skilled addressee would have recognised that there would be no material effect on the working of the Invention if the radius were longer than the average length of a human thigh bone. He noted that it was clear, even in the Specification, that the attachment points would not follow the ideal path unless the length of the lifting arm were adjusted to each individual patient for whom the device was used, and that an adjustable arm length was described as an optional feature only. He was also of the view that the skilled addressee would realise that the deviation from the "ideal" path was small enough to be immaterial.
In answer to the third question, the Hearing Officer considered it necessary to construe the claims. He thought that the use of such words as "approximately" and "comparable" and "average" made it clear that precision was not envisaged. However, in his view, the term "comparable" did impart "an intentional and meaningful limitation to the scope of the claim", and although it may not have precisely defined boundaries, "it is a clear requirement that the radius be fairly close to the average thigh length so that something approximating reasonably well to the parallelogram movement is achieved for most patients". He was of the opinion that the skilled addressee would not consider that a radius nearly 40 per cent above the thigh bone length of a tall man was intended to fall within the scope of the claim. Accordingly, the Hearing Officer answered the third question "yes" and held that the applicants' device did not infringe.
In the High Court, Jacob J emphasised that the essential purpose of the Patent was "to emulate what nurses do" (at 5). His Honour then made the observations which I set out earlier in these Reasons. A submission was made to his Honour, in terms similar to one made in the present case, that the patentee was "virtually ditching" the relevant words to treat the claim as reading:
"moved upwardly along a generally arcuate path relative to the position of the feet whereby to raise the patient to a generally standing position". (at 6)
His Lordship rejected the submission, saying that the passage in question "does implicitly deal with some positioning of the arc" which is "an arc which, effectively, keeps the patient's feet where they are and his knees, effectively, where they are" (at 6).
In the context of the present case, I also reject the submission. The words to be construed are not simply "average length of a human thigh bone" or even "comparable to the average length of a human thigh bone", but "radius comparable to the average length of a human bone". The reference to "radius" and the later references to the raising of the patient emphasise the necessity of a purposive construction. While a literal construction might suggest a comparison between measured lengths, a purposive construction calls for a comparison of motions. The references remind the addressee that the arm must be able to move sympathetically and cooperatively with the patient's femur regardless of the patient's sex, height, weight, and race, even though the lifting arm is not required by either claim 6 or claim 11 to be adjustable.
In the context of claim 6 (identical to the present claim 6), Jacob J said:
"The true construction of the expression 'radius comparable to the average length of a human thigh bone' involves consideration of the context in which the comparison is to be made. Obviously 730 as compared with 407.5 is not comparable for some purposes in some contexts. I have to look at the context here. I think the expression 'a radius comparable to the average length of a human thigh bone' must be understood in the context of what lifting motion will be produced. If a device produces a lifting motion which is substantially the same as that produced by a radius which is the same as the average length of a human thigh bone, then it is comparable." (at 9)
With respect, I agree. His Honour then referred to an exhibit which showed the arcs produced by a 450 mm thigh bone, and said:
"[t]here is a small difference in path, but I cannot believe that any nurse would think it made a blind bit of difference which path it went on. The radius of the two arcs is comparable from the point of view of this patentee. The position is the same if one uses an arc of average thigh-bone length." (at 9)
His Honour held that the Hearing Officer had erred by:
"paying too much attention to the reference to parallelograms when it is only no more than a method of trying to explain how the path of movement is produced. Of course a path of movement may matter in some context[s] very much differently from that in other contexts. Here, very broadly, in the respondents' device the patient's thigh bone and the lifting arm remain sufficiently parallel to do the job." (at 9-10)
In the present case, I have come to a similar view. The notion of what is "comparable" is not, in engineering theory or practice, a term of art. Use of words such as "comparable" and "average" shows the reader that precision is not envisaged. This is supported by references in the Specification to a "more-or-less", "approximate" and "by and large" parallelogram.
The use of the word "average" in claims 6 and 11 suggests a compromise on behalf of the drafter. Why would an "average" notion be invoked in preference to a reference to the length of the thigh bone of the particular patient coupled with provision for an adjustable length of lifting arm? Clearly, this degree of similarity was not thought to be important to the Invention. But equally clearly, there is not, for any particular patient, an advantage in having a lifting arm comparable in length to the average length of the human thigh bone rather than to the length of his or her own thigh bone.
Such considerations prompt reference to the purpose of the integer. That purpose is to give rise to comparability of the arcuate movements of the lifting arm and of any particular patient's thigh bone. How similar must those arcuate movements be? In my opinion, considerable latitude must be allowed. Perhaps the only length of lifting arm that is excluded by this integer is one that prevents the device from enabling a patient to be raised from a sitting to a generally standing position as a result of sympathetic, coordinate arcuate movement of the length of the length of the lifting arm in relation to the horizontal axis and of the patient's thighs in relation to his or her knees (as their axis).
It suffices to decide the infringement issue in the present appeal for me to say that in my opinion, the lifting arms of Nesbit's Easi-Stand Mark I and Mark II models fall within that range.
Horizontal force or pressure at the knees; and "knee abutment means"
There is no reference in claim 6 to "knee abutment means" or to the absence of horizontal force at the knees. However, as noted earlier, reference is made to these features in the body of the Specification and a knee location abutment means is mentioned in claim 11 and appears in Figures 1 and 6. Such a feature also appears in claim 10, which is dependent on claim 6. The trial Judge's understanding of the meaning of the expression "knee abutment means" and his reasons for concluding that the provision of a knee abutment means is to be implied in claim 6 were set out earlier.
Nesbit submits that claim 6 does not include a knee abutment means with any function and that claim 11 incorporates a knee abutment means with the function of locating the knees only and not of resisting significant horizontal force.
The ability or tendency to resist at least some force is an aspect of the meaning of "abutment" in ordinary English usage. If the word was intended to signify only "location" or "placement", the expression "knee location abutment means" would be tautological. This consideration alone suggests that the term "abutment" in claim 11 was not intended to mean only "placement" or "location".
The extent of forward horizontal pressure at the knees present in a particular case will be a function of the location of the horizontal axis and the length of the sling (I leave out of account the effective length of the lifting arm). Resistance to that pressure can be offered by the patient's muscles and/or by the provision of a knee abutment means. The Specification has a scheme which reveals that the drafter took these matters into account with a view to encompassing a variety of possibilities.
I have already referred to independent method claim 1 in which the integer of verticality virtually excludes forward pressure at the knees and renders muscle strength and knee abutment means unnecessary. With respect to the learned trial Judge, I think that a knee abutment means is not implied as an essential integer in apparatus claim 6. It seems to me that this is made clear by the express addition of that feature as an essential integer in dependent apparatus claim 10. The apparatus described in claim 6 will work satisfactorily, notwithstanding the absence of a knee abutment means, if the patient has sufficient muscle strength to resist forward movement of the knees. The extent of strength required will depend on the extent of "forward pull" arising from the features of construction of any particular device (for example, the horizontal axis may be only a little forward of the vertical plane previously referred to). If an apparatus eliminates the forward movement of the knees by the verticality to which I have previously referred and the appropriate angle of the sling, the method of lifting will be that described in claim 1 and the apparatus will be that described in claim 7. If it counters it by a knee abutment means, it will be the apparatus described in claim 10 or claim 11.
In sum, the patient without sufficient muscle strength to resist forward pressure at the knees is provided for by either the feature of verticality or a knee abutment means. It suffices to say that the Easi-Stand Mark I and Mark II models use the latter and infringe independent apparatus claim 11 as found by the trial Judge.
REASONING OF THE TRIAL JUDGE ON VALIDITY AND REVOCATION
It was common ground that by virtue of the operation of s 233(1) of the Patents Act 1990 (Cth), that Act, rather than the Patents Act 1952 (Cth), applied. Subsection 138 (3) of the 1990 Act provides, relevantly, as follows:
"138. ...
(3) ... the court may, by order, revoke the patent, either wholly or so far as it relates to a claim, on one or more of the following grounds, but on no other ground:
(a) ...
(b) that the invention is not a patentable invention;
(c) ...
(d) that the patent was obtained by ..., false suggestion or misrepresentation;
(e) ...
(f) that the specification does not comply with subsection 40 (2) or (3)."
The expression "patentable invention" is defined in s 18 to mean, relevantly, an invention that, so far as claimed in any claim is "useful".
Subsections 40 (2) and (3) provide relevantly as follows:
"(2) A complete specification must:
(a) describe the invention fully, ...; and
(b) where it relates to an application for a standard patent - end with a claim or claims defining the invention; ...
(3) The claim or claims must be clear and succinct and fairly based on the matter described in the specification."
The following is a summary account of his Honour's reasoning for dismissing Nesbit's cross-claim for a declaration of invalidity and an order for revocation, in so far as it is relevant to the grounds of appeal.
Fair basing - reasoning of the trial Judge
His Honour rejected the submission that the claims encompassed a quadrilateral or pentagonal lift, while the Specification was confined by reference to a "substantially parallelogram lift". Rather, he considered that both the Specification and the claims, properly construed, included a requirement of an "approximate" or "more-or-less" parallelogram in the sense explained earlier. He held that the claims did not depart from the Specification in respect of the broad construction of the phrase, "comparable to the average length of a human thigh bone".
Finally, he rejected Nesbit's submission that the claims were not fairly based on the Specification if they did not include, as an essential integer, a requirement that the lifting be performed with no horizontal force tending to displace the knees. Rather, he considered that there was an appreciation in both the Specification and the claims that while there would be no such force in an ideal situation, it would necessarily be present sometimes.
Ambiguity - reasoning of the trial Judge
The issue of ambiguity before the trial Judge was related to the following expressions:
"'radius comparable to the average length of a human thigh bone': [Claim 6];
'substantially directly above the footplate or footrests': [Claim 7];
'knee abutment means for location of the knees of the patient': [Claim 10];
'knee location abutment means':[Claim 11];
'knees of the (patient) located against said abutment means': [Claim 11];
'effective radius comparable to the average length of a human thigh bone': [Claim 11];
'with the feet ... supporting a substantial part of the total body weight of the patient ... while also supported in the standing position by the sling': [Claim 6]'."
In rejecting the charge of ambiguity, his Honour referred (at 157-8) to Minnesota Mining and Manufacturing Company v Beiersdorf (Australia) Ltd (1980) 144 CLR 253 at 274 (Aickin J, with whom Barwick CJ, Stephen, Mason and Wilson JJ concurred):
"... Lack of precise definition in claims is not fatal to their validity so long as they provide a workable standard suitable to the intended use - see British Thomson-Houston Co Ltd v Corona Lamp Works Ltd ... and Monsanto Co v Commissioner of Patents ..." (footnotes omitted)
His Honour's conclusion on ambiguity was as follows:
" ... the ... phrases ... provide simple and pragmatic criteria which are likely to be readily understood by the skilled addressee. It is true that their proper meaning was extensively debated in the expert evidence ... and in final addresses, but it does not follow that a reference to a relative expression calling for the exercise of judgment involves the imposition of an unworkable standard. I cannot accept that this ground of objection has any real force." (at 158 - emphasis supplied)
Inutility - reasoning of the trial Judge
Nesbit submits that although the claims may be construed so as to extend to patients who are unable to bear weight on their feet, the Invention requires that the patient's feet be capable of bearing approximately 40 per cent of his or her body weight during the lift. According to Nesbit, it follows that the Invention lacks utility and is therefore outside the statutory definition of "patentable invention" referred to above. His Honour thought it implicit in the object of raising a patient to a "generally standing position" that the patient must be able to bear some weight on his or her feet. That is, for his Honour, the Invention contemplated use where a patient, with the hoist's assistance, was generally able to stand, and the claims were, either expressly or by necessary implication, to be read in the light of this limitation. He referred to, inter alia, the following passage in Rescare Ltd v Anaesthetic Supplies Pty Ltd (1992) 25 IPR 119 (FCA/Gummow J) at 142:
"... a claim may have utility even though the promised advantage is not achieved in all cases".
The trial Judge rejected Nesbit's further submission that the Invention lacked utility unless the lifting arm was adjustable. In his view, there was no suggestion in the evidence that a discrepancy between the radius of the lifting arm and the "average length of a human thigh bone" (whether great or small), without more, had the consequence that the Invention did not work. His Honour said that a small discrepancy would be inconsequential and that where the discrepancy was otherwise (accepting the "more-or-less" or "approximate" parallelogram notion and his Honour's broad construction of the words "comparable" and "average"), the question would be one of degree to be resolved by reference to specific evidence which was absent in the present case.
Additionally, Nesbit submitted that the Patent lacked utility because it could not be performed without horizontal force tending to displace the knees. His Honour held that although the Patent contemplated, in an ideal form, the absence of such force, it accepted its presence as a possibility in the practical operation of the Invention.
False suggestion and misrepresentation - reasoning of the trial Judge
Nesbit argued that the Patent contained an illusory promise that the Invention could work without horizontal force tending to displace the knees. The trial Judge thought that although the Patent envisaged that situation as an "ideal" or "preferred" embodiment, it also envisaged a more "practical" one. He considered that the Specification made it clear that for some patients there would be horizontal force at the knees, and noted that each of Nesbit's experts accepted that the Patent "teaches that there may be some force at the knees in the course of working the invention".
PARTIES' SUBMISSIONS AND REASONING ON THE APPEAL RELATING TO VALIDITY AND REVOCATION
The grounds of appeal relied on by Nesbit sufficiently appear from the following outline of the parties' submissions and my earlier reasoning on the appeal in relation to infringement.
Fair basing - parties' submissions and reasoning on the appeal
Nesbit submits that the claims are not fairly based on matter described in the Specification because:
(a) they include a quadrilateral or pentagonal lift and are not confined to what can properly be described as a substantially parallelogram lift;
(b) they encompass the situation where the radius of the arc of the lifting arm is up to three times the length of an average human thigh bone; and
(c) "the Invention" does not include as an essential integer or feature, a requirement that the lifting be performed with no horizontal force tending to displace the knees.
In response, Impro-Arjo submit that an apparatus possessing the features claimed in claim 6 and one possessing the features claimed in claim 11 are described in the Specification as examples of preferred embodiments, that it is therefore not open to conclude that the claims are not fairly based on matter described in the Specification, and that it cannot be said that "the claim, as expressed, travels beyond the matter disclosed in the specification": Olin Corporation v Super Cartridge Co Pty Ltd (1977) 180 CLR 236 at 240 (Barwick CJ).
The relevant principle to be applied is explained by Gummow J in Rehm Pty Ltd v Websters Security Systems (International) Pty Ltd (1988) 11 IPR 289 (at 304):
"... the question is whether there is a real and reasonably clear disclosure in the body of the specification of what is then claimed, so that the alleged invention as claimed is broadly, that is to say in a general sense, described in the body of the specification."
I agree with the trial Judge that both the Specification and claims 6 and 11, properly construed, include a requirement of an "approximate" or "more-or-less" parallelogram and parallelogram lift, understood in the limited sense explained earlier. Therefore I reject Nesbit's submission (a).
Nor do I accept Nesbit's submission (b). The expression "comparable to the average length of a human thigh bone" is used in both the Specification and the claims. Nesbit has not suggested, and could hardly suggest, that it bears different meanings in the two places. In any event, the trial Judge did not hold that the claims encompass a device with a lifting arm up to three times the average length of a human thigh bone. In fact, his Honour emphasised that a purposive reading requires regard to be had to the objectives of compactness and mobility, which necessarily impose a limit on the arm's length.
Nor is lack of fair basing established in relation to the issue of absence of horizontal force at the knees (Nesbit's submission (c)). For the reasons given in relation to infringement, the apparatus claims do not include this feature as an essential integer. I agree with the trial Judge that the body of the Specification shows that while the absence of horizontal force at the knees is preferable, that is an "ideal" situation, and the Specification envisages that such force will be present on some occasions and will then be countered by muscle strengths and/or a knee abutment means. Nesbit points to the sentence in the Specification which says that "[t]he result is that the lifting is performed with no horizontal force tending to displace the knees". However, that sentence occurs in the first consistory statement which relates to claim 1, a method claim. The expression does not occur in the second or third consistory statements on which apparatus claims 6 and 11 are based.
In any event, within the first consistory statement, the sentence must be read in context. The context includes the following passages:
"[The pivot point] remains fixed relative to [the] footplate or footrests and is disposed substantially directly above the heel position of the patient ..."
"The knees of the patient may initially be located against knee abutment means of the hoist."
"Preferablyknee abutment means are mounted on the support structure so that the knees are not displaced but can remain at rest against the knee abutment means, the lower legs remain vertical thus ensuring that their own weight and half the thigh weight is supported by the feet on the footplate or footrests and there is no transference of this weight to be taken by the sling. This is an important feature contributing to patient comfort as it minimises the pressure on the body of the sling in lifting the balance, which may be approximately 60%, of the body weight." (emphasis supplied)
It is the vertical alignment of horizontal axis, knee abutment means and heels of the patient that eliminates forward movement of the knees in the method described. Verticality is not taught in the second or third consistory statements and is not an integer of corresponding apparatus claim 6 or claim 11.
Knee abutment means are present in all of the embodiments illustrated in the accompanying drawings. Their presence in Figure 1 is described as follows in the Specification:
"Knee location abutment means are provided by a knee pad ... mounted on the front of the column ... for engagement with the knees of the patient ... during initial positioning of the hoist and during lifting, with the feet of the patient resting on separate footrests... mounted on the chassis cross member ... on opposite sides, respectively, of the socket .... ... In this position infirm and seriously disabled patients will be supported with the knees still in engagement with the knee pad ..., but patients with sufficient muscular tone will involuntarily straighten the knees and thus be supported with the body completely straight." (emphasis supplied)
The Specification describes their presence in Figure 6 in these terms:
"The lifting of an infirm or seriously disabled person is illustrated in full lines in Figure 6, as shown the knee region engaging the abutment means KA at all times even when in the final standing, and slightly backwardly-inclined, position. However, patients with sufficient muscular strength will involuntarily straighten their legs during lifting so that, in the final position the body is completely straight between the footrests or footplate F and the sling S. Thus for these patients the abutment means KA merely provide location at the initial stage of the lift." (emphasis supplied)
Knee pads are also present in the description of the hoist illustrated in Figures 4 and 5 (not reproduced in these Reasons).
With respect, I agree with the trial Judge's conclusion that the knee abutment means are recognised in the Specification as having a dual purpose. Where the device possesses the verticality mentioned or the patient has sufficient muscular strength in the legs or both of these conditions are satisfied, a knee abutment means can serve only the "minor" function of initial "positioning" or "location". But where that verticality is not a feature of the particular device and the patient lacks sufficient muscular strength to resist the forward displacement of the knees, a knee abutment means will perform that role.
In the light of these matters, it cannot be reasonably maintained that the body of the Specification does not accept the possible presence of horizontal force at the knees at all and that a knee abutment means only ever serves the minor purpose of "location" or "positioning" at the initial stage of the lift. Expert evidence, not substantially challenged, made it clear that more or less horizontal force will be present at the knees according to, for example, the position of the horizontal axis and the angle of the sling, neither of which is the subject of an integer in claim 6 or claim 11.
Ambiguity - parties' submissions and reasoning on the appeal
Nesbit submits that each of the seven expressions set out earlier is central to the Invention, and causes difficulty for the skilled addressee or manufacturer who wants to ascertain whether some proposed activity will infringe the Patent.
Impro-Arjo submit that none of the witnesses demonstrated any difficulty in understanding the meaning of the terms identified, although they disagreed over what they regarded as the "intent" of the Invention, a disagreement which, according to the submission, does not establish ambiguity. Impro-Arjo submit that it is not unusual for claims to be defined partly by reference to relative expressions which call for an exercise of judgment, and that provided they afford a workable standard, they will be valid.
Two of the allegedly ambiguous expressions are found in claims 7 and 10 set out earlier. A finding of invalidity based on them would not affect claims 6 and 11, in respect of which the claim of infringement is made. Impro-Arjo complain that some of the phrases referred to by Nesbit were not in issue before the trial Judge. However, they are referred to in his Honour's Reasons for Judgment.
From the evidence, it is clear that none of the witnesses had difficulty in understanding the meaning of the terms in question. However, they differed in their views as to the substance of that meaning. It does not follow that the claims are ambiguous..
It is well established that the reason why the claims are required to define the invention clearly and succinctly is that readers should be able to ascertain the precise extent of monopoly claimed. If a claim is ambiguous, the ambiguity may be resolved by reference to the body of the Specification, failing which the claim is invalid. In Tye-Sil Corp Ltd v Diversified Products Corp (1991) 20 IPR 574 (Can/Fed CA), De Cary JA said (at 585):
"The specification of a patent is directed to a person skilled in the art and should be given a purposive construction rather than a purely literal one derived from applying to it meticulous verbal analysis. Where the language of the specification, upon a reasonable view of it, can be so read as to afford the patentee protection for that which he has actually in good faith invented, the court, as a rule, will endeavour to give effect to that construction and will not defeat the right of patentees for mere technicalities." (footnotes omitted)
As Impro-Arjo submit, it is not unusual for a claim to define an invention partly by the use of a relative expression which necessitates exercise of judgment (see, for example, Elconnex Pty Ltd v Gerard Industries Pty Ltd (1992) 25 IPR 173 (FCA/FC) at 190 (Lockhart J); Populin v HB Nominees Pty Ltd (1982) 41 ALR 471 (FCA/FC) at 477 et seq; Leonardis v Sartas No 1 Pty Ltd (1996) 35 IPR 23 (FCA/FC) at 32-33 and cases there cited; Blanco White, Patents for Inventions (5th edn, 1983) at par 2-112) and so long as the claims provide a workable standard suitable to the intended use, they will be valid (Minnesota Mining & Manufacturing Co v Beiersdorf (Australia) Ltd (1980) 144 CLR 253 at 273 et seq (Aickin J)). The expressions in question must be understood in a practical, commonsense manner.
The three expressions which include "abutment means" are, in my opinion, readily understandable by the skilled addressee. I am not persuaded that they exhibit ambiguity. Nor, in my opinion, does the expression "substantially directly above the footplate or footrests" in claim 7 or the expression "with the feet ... supporting a substantial part of the total body weight of the patient ... while [the patient is] also supported in the standing position by the sling" in claim 6. The words "substantially" and "substantial" do not, in my view, render ambiguous the expressions in which they occur; cf Vax Appliances Ltd v Hoover Plc [1991] FSR 307 (Aldous J) at 309, 318 ("substantially dropwise" flow); Monsanto Co v Commissioner of Patents (1974) 48 ALJR 59 ("substantial effect"); Leonardis v Sartas No 1 Pty Ltd, supra ("substantially above").
The remaining two expressions attacked turn on the expression "radius comparable to the average length of a human thigh bone". It is true that the parties differed in their views as to the meaning of this expression, that it has been necessary to resort to the Specification in the process of its construction, and that its construction has been a matter of some difficulty. The use of the relative expression "comparable" requires a comparison of measurements or poses a "functional" test. However, these considerations do not, without more, indicate that the expression is ambiguous. In my view, the skilled addressee would understand that the expression is not intended to refer to anthropometric data, and is to be understood in the context of a requirement of a sympathetic, coordinated and generally similar arcuate movement of the lifting arm and the patient's thighs. In my respectful opinion, his Honour correctly held that this expression is not ambiguous either.
Inutility - parties' submissions and reasoning on the appeal
Nesbit makes submissions generally along the following lines:
Firstly, the claims define an Invention in relation to "the lifting of invalid patients, which term includes infirm and disabled persons generally". This expression is wide enough to include patients who cannot use their feet, such as quadriplegics, amputees, and patients who are unable to bear weight on their feet to the extent required by the Invention. The claims lack utility in that they require the patient to be able to bear approximately 40 per cent of his or her own body weight during lifting.
Secondly, the Invention cannot work unless the length of the lifting arm is adjustable, and can be extended to a length comparable to the average length of the human thigh bone (or any length within the range of lengths which is considered to be so comparable).
Thirdly, the Invention cannot be performed without horizontal force tending to displace the knees.
Fourthly, as the scope of each claim includes some method which is not useful, each claim is invalid: Norton and Gregory Ltd v Jacobs (1937) 54 RPC 271 at 276-7 (Lord Greene MR); Minerals Separation North America Corp v Noranda Mines Ltd (1952) 69 RPC 81 at 95 (Lord Reid); Coopers Animal Health Australia Ltd v Western Stock Distributors Pty Ltd (1986) 6 IPR 545 at 572-3 (Wilcox J); Pracdes Pty Ltd v Stanilite Electronics Pty Ltd (1996) 35 IPR 259 at 273 (NSWSC/Windeyer J).
Impro-Arjo make submissions in reply generally along the following lines:
To say that the Invention was intended to be used for all invalids, including those who are unable to use their legs, for example, amputees, is to misconstrue the Patent. Properly construed, the claims are limited to situations where a patient can stand with the hoist's assistance: Atlantis Corp Pty Ltd v Schindler (1995) 33 IPR 91 (NSWSC/McLelland CJ in Eq) at 97-8; International Business Machines Corp v Commissioner of Patents (1991) 22 IPR 417 (FCA/Burchett J). The witnesses did not think that the hoist was intended to be used by patients unable to bear weight.
There is no evidence that the Invention does not work where there is a discrepancy between the radius of the lifting arm and the average length of a human thigh bone.
A claim may have utility even though the promised advantage is not achieved in all cases: Rescare Ltd v Anaesthetic Supplies Pty Ltd (1992) 25 IPR 119 (FCA/Gummow J). The present case is not one in which a claim includes embodiments which are inutile for their intended purpose. The intended purpose here is, of necessity, to raise the patient to a generally standing position. Inherent is a requirement that the patient have such weight bearing capacity that, with the aid of the hoist, he or she is able to stand.
To insist, as Nesbit's submission does, that the Invention was intended to be used for all patients, regardless of whether they do not have any use of their legs, is a misconstruction. Properly construed, the claims are, expressly or by necessary implication, limited to situations in which a patient can stand with the hoist's assistance: see International Business Machines Corp v Commissioner of Patents (1991) 22 IPR 417 (FCA/Burchett J) at 421-422. No witness thought that the hoist was intended to serve the needs of amputees or patients unable to bear weight through their feet. A claim may have utility even though the promised advantage is not achieved in all cases: Rescare Ltd v Anaesthetic Supplies Pty Ltd (1992) 25 IPR 119 (FCA/Gummow J) at 142. The present case is not one in which a claim includes embodiments which are not useful for their intended purpose. The intended purpose is to raise the patient to a generally standing position. Inherent is the requirement that the patient be able to stand, albeit with external support.
Secondly, I do not accept Nesbit's submission that the Invention cannot work unless the length of the lifting arm is adjustable, to conform to a length comparable to the average length of the human thigh bone (or any length within the range of lengths which might be considered to be comparable to the average length of the human thigh bone). No evidence was led to demonstrate that the Invention does not work where there is a discrepancy between those two lengths. In fact, Nesbit's own devices afford evidence to the contrary.
Thirdly, the submission that the Invention is inutile in that it cannot operate without horizontal force tending to displace the knees, must fail in the light of my view that it is not an object of claim 6 or claim 11 that the apparatus described always operate without such force. The Specification and claims anticipate the presence of some such force. As this ground overlaps with the submissions made in relation to the issues of fair basing and false suggestion or misrepresentation, I refer to, rather than repeat, my reasoning on those issues.
Fourthly, it is not true to say that each claim includes some method that is not useful. This result follows from my resolution of the issues of construction earlier.
Insufficiency - parties' submissions and reasoning on the appeal
Nesbit submits that the Specification uses terms which lack certainty; that the patentee has failed to provide complete disclosure of the Invention such that a skilled addressee in the field may understand how it works; and that the term "comparable" is a relative one which requires recourse to data as to the length of the human thigh bone which cannot be ascertained from the Specification.
Impro-Arjo reply that the patentee does not seek to define the Invention by reference to anthropometric data or to introduce precepts of ergonomic design; that the phrase "average length of a human thigh bone" is used merely to refer to "the common run" for the purposes of a broad comparison; and that even if Nesbit's construction of the claims is correct, they do not fail for insufficiency as such data, although limited, is available and did not have to be set out in the Specification. Impro-Arjo submit that the witnesses did not suggest that the claims were insufficient in the present respect.
As expressed in Nesbit's written submissions, this ground of attack is partly repetitive of the matters raised in relation to ambiguity. In my view, Impro-Arjo's submissions should be accepted.
False suggestion and misrepresentation - parties' submissions and reasoning on the appeal
Nesbit's submissions proceeded along the following lines:
The promise in the Specification that the Invention can be implemented with no horizontal force tending to displace the knees is illusory. This was a material misrepresentation which would have substantially influenced and misled the Commissioner in his decision to grant the Patent: Prestige Group (Aust) Pty Ltd v Dart Industries Inc (1990) 26 FCR 197 (FC) at 201 (Lockhart J).
[Nesbit further submits that the trial Judge impermissibly drew an inference adverse to Nesbit from the absence of explanation by Nesbit as to the difference between the lengths of the lifting arms of the Easi-Stand Mark I and II models, and that absence of explanation cannot, without more, be used to construct an adverse admission, especially where the evidence did not suggest an issue calling for explanation: Jones v Dunkel (1959) 101 CLR 298 at 308 (Kitto J), 312 (Menzies J) and 320-1 (Windeyer J); Whitehorn v R (1983) 152 CLR 657 at 690 (Dawson J).
Impro-Arjo's submissions in reply proceeded along the following lines:
For a misrepresentation to invalidate, it must have materially contributed to the Commissioner's decision to grant the Patent, even if other factors also formed part of the decision-making process: Prestige Group v Dart Industries (1990) 26 FCR 197 at 201 (Lockhart J) and at 218 (Gummow J). This requirement is not met in the present case.
The alleged misrepresentation is that "the result is that the lifting is performed with no horizontal force tending to displace the knees". That phrase does not stand unqualified. Dr Stark stated in cross-examination that the Patent was "wrong" in this respect. The Patent does not claim that there is no horizontal force at the knees and, to the contrary, provides for a knee abutment means.
The Patent was not obtained upon the alleged misrepresentation. The Specification anticipates that in some instances there will be force at the knees.
The Specification does not represent that an express object of the Invention, or advantage over the prior art, is that there is no horizontal force at the knees. Hence it cannot be maintained that the Patent was obtained on a misrepresentation.
Nesbit's witnesses acknowledged in cross-examination that the Specification teaches that there may be force at the knees during the operation of the claimed device.
A mere incorrect theoretical explanation in the Specification of the working of the Invention, or an erroneous statement in the body of the Specification, even if carried over into the claims, will not vitiate the Patent if it is otherwise valid: Atkins and Applegarth v The Castner-Kellner Alkali Co Ltd (1901) 18 RPC 281 (Buckley J) at 293-4; CCOM Pty Ltd v Jiejing Pty Ltd (1994) 51 FCR 260 (FC) at 282.
In any event, invalidity on this ground affects only claims 1-5, not the apparatus claims 6 and 11.
Nesbit submits that the Specification misrepresents that "[t]he result is that the lifting is performed with no horizontal force tending to displace the knees". For a misrepresentation to invalidate a patent, it must have "materially contributed to the Commissioner's decision to grant the patent even if other circumstances or causes also played a part in the making of that decision": Prestige Group (Aust) Pty Ltd v Dart Industries Inc, supra, at 201 (Lockhart J) ("Prestige"). It is sufficient if the conduct is a material inducing factor leading to the grant: Prestige at 201 (Lockhart J), 218 (Gummow J). The rationale is explained in Prestige by Lockhart J (at 199):
"if [the patentee] asserts an inventive merit of his invention and promises a particularly beneficial or useful result, this may persuade members of the public into believing his claims are valid and act[ing] on the faith of that by, for example, becoming a licensee or by not using the alleged invention."
Nesbit submits that the Commissioner would have been substantially influenced and misled to accept that the Invention necessarily involves absence of horizontal force at the knees. However, I have explained earlier why I do not think that absence of horizontal force at the knees is an integer of claim 6 or claim 11. It is possible to build devices in accordance with those claims which will give a lifting action involving horizontal force at the knees.
Nesbit's expert witnesses, Dr Ackland and Dr Cheng, acknowledged in cross-examination that the Specification teaches that there may be force at the knees during the operation of the claimed device. No misrepresentation in this respect could have materially contributed to the Commissioner's decision to grant the Patent.
Dr Stark stated in cross-examination that the proposition alleged to form the misrepresentation (that is, that the lifting is performed without horizontal force tending to displace the knees) was "wrong". But a factually erroneous statement in the body of a Specification (as alleged in the present case), even if carried over into the claims, does not vitiate an otherwise valid patent: Atkins and Applegarth v The Castner-Kellner Alkali Co Ltd (1901) 18 RPC 281 (Buckley J) at 293-4; CCOM Pty Ltd v Jiejing Pty Ltd (1994) 51 FCR 260 (FC) at 282. However, this proposition is qualified by the proviso that "from a practical point of view the public concerned [must be] fairly given possession of the invention": Adhesives Pty Ltd v Aktieselskabet Dansk Gaerings-Industri (1935) 55 CLR 523 at 546 (Evatt J).
The present ground of invalidity is not made out.
CONCLUSION
In my opinion, for the reasons stated above, the appeal should be dismissed with costs.
I certify that this and the preceding sixty-two (62) pages are a true copy of the Reasons for Judgment herein of the Honourable Justice Lindgren