CONSTRUCTION OF THE PATENT
46 The symbol (+), which appears in Claim 1, indicates the particular enantiomer that is distinguished by the property of rotating plane-polarised light to the right. The property of rotating plane-polarised light to the right or to the left distinguishes one enantiomer from the other and distinguishes each enantiomer from the racemate. That property is able to be detected only when the relevant enantiomer is present other than as a part of the racemate because, when in a racemic mixture, the polarisation of light by each enantiomer is cancelled out by the polarisation by the other enantiomer. No net polarisation of light is therefore exhibited.
47 The primary judge concluded that the skilled addressee as at the priority date of Claim 1 would have understood Claim 1 to refer specifically to the (+)-enantiomer and not to either the (-)-enantiomer or to the racemic mixture of the two enantiomers. His Honour considered that such a skilled addressee, in the absence of any context suggesting the contrary, would not have understood Claim 1 to refer to the (+)-enantiomer merely as part of the racemic mixture consisting of equal parts of the (-)-enantiomer as well as the (+)-enantiomer. His Honour found that such a skilled addressee would have understood Claim 1 to refer to the (+)-enantiomer as something that had an existence independent of the racemic mixture.
48 The primary judge accepted that it was part of common general knowledge as at the priority date of Claim 1 that:
· Racemates contained in equal parts the (+)-enantiomer and the (-)-enantiomer.
· The enantiomers of a racemate are potentially separable and it was possible that an enantiomer might have a stable existence as a compound separate from being part of the racemate.
· Some racemates had in fact been resolved into their separate enantiomers.
· Racemates were commonly represented by the symbol (+/-) to indicate the presence of both enantiomers.
49 The primary judge accepted that the (+)-enantiomer of the Citalopram compound exists when it is part of the racemate. However, his Honour considered that the relevant skilled addressee would have understood that the (+)-enantiomer exists whether or not it is a part of the racemate, and that the purpose of the (+) symbol is only to distinguish it from the (-)-enantiomer and from its being merely part of the racemate (+/-) or of some other mixture. His Honour concluded that the (+) symbol or the (-) symbol, devoid of any context suggesting the contrary, implies distinctness from the racemate. His Honour concluded, accordingly, that the reference to the (+)-enantiomer in Claim 1 refers to something different from the (+)-enantiomer as an indistinguishable part of the unresolved racemate.
50 His Honour considered that, when the (+)-enantiomer of Citalopram is present only as 50% of a racemic mixture, it does not meet the description in Claim 1. However, his Honour accepted that, in the absence of anything further, the question of how much impurity would prevent a compound from meeting the description in Claim 1 is not specified in Claim 1 or the Specification. Nevertheless, his Honour concluded that a convention as to the way in which chemists understand references to compounds would answer that question. His Honour concluded that, according to that convention, the reference in Claim 1 denotes material of at least 95% enantiomeric purity.
51 As indicated above, Alphapharm and Arrow dispute the construction of Claim 1 propounded by Lundbeck and accepted by the primary judge. The question of construction is whether Claim 1 refers only to the (+)-enantiomer in an isolated form and not to the (+)-enantiomer in a mixture, such as would be found in the racemate.
52 The primary judge summarised the approach that he took to the construction question as follows:
· The construction of a specification is a question of law and is a matter for the Court, although the Court must construe a specification as it would be understood by the notional skilled addressee as at the relevant date. Evidence from a skilled addressee in the field of the invention as to how he or she would have understood the specification at the relevant date is admissible evidence.
· The claims of a specification must be construed in the context of the complete specification as a whole: the rest of the specification may explain the background to the claims, assist in ascertaining the meaning of technical terms or aid in the resolving of ambiguities in the construction of the claims.
· A specification must be given a purposive rather than a purely literal construction and must be construed in a practical commonsense manner, avoiding a too technical or narrow construction in favour of a construction under which the invention will work, as against one according to which it may not work.
· The hypothetical addressee of a patent is the non-inventive person, with the common general knowledge of a person, skilled in the relevant art at the priority date.
· The words used in the specification and the claims of a patent are to be given the meanings that that skilled addressee would give them, both in the light of his or her own general knowledge and what is disclosed in the body of the specification.
53 While the last proposition is correct, and evidence as to how the hypothetical addressee would have understood a specification at the relevant date may strictly be admissible, the underlying principle is that contained in the first proposition stated above, namely, that the construction of a specification, including the claims, is a question of law for the Court. However, the Court may be informed, for example, as to the way in which particular terms were, as a general rule, used by relevant addressee at the relevant time or what the use of a particular term or expression disclosed or conveyed to a relevant addressee at the relevant time, so long as it is shown that an understanding different from the ordinary usage of English was generally accepted by relevant addressees.
54 In that regard, there should be no difference in the approach to the construction of a patent from the approach to the construction of any other commercial instrument. That is to say, neither a patent nor any other commercial instrument should be construed in a vacuum but must be construed in the context in which the patent or instrument is being considered. Thus, the claims and specification of a patent must be construed in the way in which they would be understood by the relevant addressee. In the same way, a commercial instrument would be construed in the light of facts that might reasonably be expected to be known to the parties to the commercial instrument.
55 The primary judge held that the (+) in Claim 1 indicated the particular enantiomer that is distinguished by the feature of rotating plane-polarised light to the right, namely clockwise, which distinguishes that enantiomer from the other enantiomer, which has the property of rotating plain polarised light to the left, namely anti-clockwise. That property is able to be detected only when the relevant enantiomer is isolated from the other enantiomer. When it is present only as part of the racemate, or a racemic mixture, the polarisation of light by each enantiomer is cancelled out by the other enantiomer. Thus, his Honour held that the skilled addressee of the Patent in 1988, the priority date, would have understood Claim 1 to refer specifically to the (+)-enantiomer, isolated from the (-)-enantiomer.
56 Alphapharm and Arrow complain that the primary judge erred in that construction of Claim 1 by impermissibly adding one or more integers that are not to be found in Claim 1. Alphapharm and Arrow contend that the correct construction of Claim I is for a unique molecule possessing a unique, three dimensional configuration. Claim 1 does not specify purity: it does not do so because what is claimed is the molecule itself. Claim 1 does not refer to the solution or other environment in which the molecule is found. It does not refer, by exclusion or otherwise, to the racemate or any other mixture. They say that, while Lundbeck might have intended to cover the (+)-enantiomer, it did not limit itself to the pure enantiomer, in the wording of Claim I. Thus, they say, Claim 1 will be infringed by the independently existing (+)-enantiomer, but it will also be infringed by the racemate, which, by definition, includes the (+)-enantiomer.
57 Alphapharm and Arrow contend that the primary judge erred in reading into Claim 1, three additional integers as follows:
· First, his Honour read in the additional limitation of "independently existing" or "existing independently of the racemate".
· Secondly, his Honour read in a degree of purity, namely, 95%.
· Thirdly, his Honour read in a type of purity.
58 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. Because a patent operates as a public instrument, the monopoly must be expressed in such a way that it is not capable of being misunderstood. The plain and unambiguous meaning of a claim cannot be varied or qualified by reference to the body of the specification (see Welch Perrin & Co Pty Ltd v Worrel (1961) 106 CLR 588 at 610 and Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 207 CLR 1 at [15]).
59 Alphapharm contends that the primary judge erred in that, while Claim 1 refers simply to (+)-Citalopram, his Honour read in the words "otherwise than as part of the racemate" that could include the proportions 60:40, 80:20; 90:10 and so on. His Honour then read in a further integer to limit that lack of clarity, by reading in a degree of purity of 95%. It may be that his Honour was intending to refer to enantiomeric purity, which is referred to in Claim 6. However, the only type of purity described in the body of the Specification is optical purity.
60 There is no warranty for adopting a method of construction that gives a patentee what it might have wished or intended to claim, rather than what the words of the relevant claim actually say. While such an approach may be appropriate where there is a genuine ambiguity, it is not permissible to read an entire limiting integer into the claim as written, when the claim clearly does not contain it.
61 Claim 1 is for the (+)-enantiomer of the compound shown in the diagram on page 1 of the Specification. There is no reason why Claim 1 should be construed as referring to anything other than the enantiomer as a substance. There is nothing in Claim 1 to indicate that the reference is intended to be to the (+)-enantiomer isolated from the (-)-enantiomer. Putting aside how the relevant skilled addressee might understand the reference in Claim 1, Claim 1 by itself simply identifies the substance, in whatever surroundings it may exist.
62 There is indeed force, as the primary judge accepted, that the use of words such as "individual", "pure", "separated" and "isolated", in the body of the Specification indicates that when reference was made to the (+)-enantiomer in Claim 1, without the use of such qualifying words, Claim 1 was intended to mean what it says, namely, the substance in the abstract, irrespective of its physical contiguity with other substances, such as the (-)-enantiomer.
63 The primary judge referred to a number of textual matters in the body of the Specification that were relied upon by Lundbeck as supporting its construction. His Honour considered that, if Claim 1 is ambiguous, the Specification as a whole teaches that Claim 1 refers to the independently existing (+)-enantiomer, and not to merely the (+)-enantiomer, when a part of unresolved (+/-)-Citalopram. However, his Honour did not consider that Claim 1 is ambiguous and, accordingly, did not in his reasoning have regard to those textual matters.
64 Once those textual matters are put aside, however, there is no real reason for applying anything other than a literal construction of Claim 1. Claim 1 is for the product or substance, namely, the (+)-enantiomer. It is not permissible to construe a claim or the specification with a view to avoiding the effect of prior documents. His Honour observed that, in the absence of a context permitting otherwise, the relevant skilled addressee would not have understood the claim to the invention of (+)-Citalopram to refer to that compound merely as part of the unresolved racemate. Rather, his Honour said, the skilled addressee would have understood the claim to the invention of (+)-Citalopram to refer to that compound as something that had an existence independent of that of the racemate.
65 It is correct, as his Honour says, that the reference in Claim 1 is a specific reference to the enantiomer of Citalopram that rotates plane-polarised light to the right. However, his Honour then says that the reference is not apt to refer to the (+)-enantiomer merely as present in the racemate. The reasoning given for that conclusion is that there is no context suggesting a different possibility. However, the task is to construe the words of Claim 1. Those words describe a product or substance. They do not suggest in any way that the product or substance must be isolated from other products or substances. There is nothing in Claim 1 to suggest that the (+)-enantiomer is disclosed with a degree of purity. The racemate is no more than a mixture of the two enantiomers. Each of those two compounds is present in the racemate and can be separated. Further, at the relevant time, the relevant hypothetical skilled addressee was aware that the racemate contained both compounds and that the two compounds could be separated.
66 It may be that some inference can be drawn that Lundbeck, in applying for a patent in respect of the (+)-enantiomer, was intending to claim something that had not been disclosed by the Citalopram Patent. If so, it would have been a simple matter to specify in Claim 1 an integer requiring that the substance disclosed be separate from the (-)-enantiomer. Thus, it would have been possible to amend Claim 1 to specify "substantially pure (+)-Citalopram". Alternatively, Claim 1 could have been qualified by claiming the (+)-enantiomer "substantially free of" or "substantially separated from" the (-)-enantiomer. No such qualifying words are to be found in Claim 1. To read into Claim 1 such qualifying words is impermissible as a matter of construing the clear and unambiguous words used by Lundbeck.
67 It follows that the primary judge erred in his Honour's construction of Claim 1.