4.2.2 Consideration
60 I accept the construction advanced by Cytec. In my view, each of the amended claims includes within its scope a product mixture consisting of only the listed small molecules.
61 Looking first at the language of amended claim 1, the method there involves adding to the Bayer process stream an aluminosilicate scale inhibiting amount of a composition "comprising" the small molecules identified in integer (3) within a product mixture formed from the reaction of A, GPS and E. The requirement of integers (2) and (3) is that all of the small molecules identified must be present in the product mixture, although given the inclusive definition of "comprising" in the specification, other components may also (optionally) be present.
62 That construction is consistent with the findings at J[108] in respect of the current version of claim 1:
The result is that, properly construed, the claim includes within its scope both: (a) a complex reaction mixture, formed from the reaction of A + GPS + E, that includes within it many of the identified small molecules as well as many more compounds; and (b) a reaction mixture, formed from the reaction of A + GPS + E, that is made up of a single type of small molecule identified in the claim. The language of "comprising at least one small molecule" indicates that the claim covers the spectrum between these two possibilities.
63 I see no reason why a different construction of the word "comprising" in the context of the claim would arise from the language of amended claim 1. Although the amended claims refer to a number of specified small molecules (varying in amount from 3 to 13 or 14) rather than a single small molecule, the logic of J[108] still applies. The amended claims require at a minimum that the specified small molecules be present. Many more may be included, but that is not essential.
64 I do not accept Nalco's submission that the words "within a product mixture formed from the reaction of A, GPS and E", which appear in the current version of claim 1, would now be understood by the person skilled in the art to mean that the amended claims do not include within their scope a product mixture that only contains the small molecules listed. Read as a whole, the language of amended claim 1 more sensibly has the meaning that the product mixture may be made up of those specified molecules only or made up of those specified molecules as well as others. I am fortified in that conclusion by the evidence of the experts in the Joint Expert Report, who agreed, in relation to the proposed amended claims:
All the small molecules illustrated and referred to by Roman numerals in each claim must be present in the product mixture of that Claim. No other small molecule is either excluded or required. That is, other small molecules may also be present in the product mixture, but the Claim does not require or exclude the presence of any other material in the product mixture.
65 In support of its submission, Nalco draws attention to the evidence of the experts that it is, in effect, impossible to create a reaction mixture from A, GPS and E that results only in the specified small molecules. It submits that whilst the words "within" and "formed" are ordinary English words, the term "product mixture" is a term of art such that the skilled addressee would understand those terms together to mean that the claims do not include within their scope a product mixture that only contains the small molecules listed.
66 However, the expression "term of art", and the role of the expert evidence should be correctly understood. The words "product mixture" are part of a phrase, being "product mixture formed from the reaction of [A + GPS + E]", that describes, as the expert evidence explains, how a product mixture is created and the end result of that product mixture. The words "product mixture" themselves are ordinary English words that are to be understood in that technical context. Explaining the technical context falls within the realm of expert evidence but determining the meaning of the words "product mixture" is a matter for the Court. To the extent that Nalco's submission suggests that the Court is bound by an expert's construction of "product mixture", I reject that proposition. As the Full Court said in Commissioner of Patents v Rokt Pte Ltd [2020] FCAFC 86; (2020) 277 FCR 267 at [73] (Rares, Nicholas and Burley JJ):
The role of expert evidence in construing the patent specification and the claims is limited. It is to place the Court in the position of the person acquainted with the surrounding circumstances as to the state of the art and manufacture as at the priority date: Kimberly-Clark Australia Pty Ltd v Arico Trading International Pty Ltd (2001) 207 CLR 1 at [24]; Myriad Genetics at [12]. Typically, the Court will read the specification with the benefit of expert evidence as to the meaning of words that are terms of art, or with an explanation of technical concepts relevant to the understanding of the invention as described and claimed. The question of construction remains with the Court.
67 Nalco also submits that the word "comprising" supports its position, because the words "including, but not limited to" would be understood in the context of the reaction mixture to mean that the small molecules are to be within the product mixture so formed, which will invariably contain the identified small molecules as well as many others.
68 In my view the principles of construction set out at J[91] do not support that approach. The plain meaning of "comprising" is that the composition of the amended claims will include at least the specified compounds within the reaction mixture but may contain more than those compounds. One may not distort the clear language of the claim by reference to glosses drawn from the specification or elsewhere. The tortured history of amendments of the claims identified in section 1.2 above demonstrates, even if it were not a given in patent law, that the language of the claim is of the patentee's own choosing. If the patentee wished to signify that only product mixtures containing more than the specified molecules were present in the product mixtures, then it could have done so.
69 In contesting this construction, Nalco accepts that it is practically not possible to specify the outcome of the reaction of A, GPS and E such that any individual small molecule, or group of small molecules is produced. It submits that this aids its construction, noting that when one of the three different forms of amine is reacted with GPS and E, the consequent product mixture will always contain an extremely large variety of small molecules and will include all the small molecules listed in the current and amended claims, as well as many others, and polymers. It contends that because it is not practically possible to react A, GPS and E in a way that results only in those small molecules being present to the exclusion of other small molecules or polymers it is not practical or within common sense to construe the claims in the manner set out above. As I have noted, that is not the approach taken by the experts, who were well familiar with the practical difficulties to which Nalco refers but still read the plain words of the claims for the meaning to which I have referred at [64] above.
70 Nalco submits that the evidence of Mr Bellwood, in agreeing to the passage from the Joint Expert Report quoted above, should not be determinative of the small molecule construction issue. It submits that the substance of Mr Bellwood's evidence elsewhere was such that he would never have agreed to that construction of the claim if it had been pointed out to him that the consequence was that the amended claims included within their scope a product mixture containing only the specified small molecules, because he considered that this was impossible to achieve. Nalco complains that it was not permitted to "explore this during the oral expert evidence" on the basis that construction was a matter for the court.
71 The proposition advanced by Nalco is, in effect, that it ought to have had an opportunity to cross examine its own witness in order to enable it or him to retreat from a clear concession that he made in joint session and produced in a joint expert report. Mr Bellwood was a careful and well qualified witness whose evidence reflected a clear understanding of the issues in the case. He joined in the answer given above in a manner that was consistent with the construction that I have (separately) adopted.
72 There are three reasons why Nalco was not permitted to cross examine its own witness.
73 First, to do so would undermine the process of the preparation and presentation of joint expert reports and evidence. Unless an expert witness wishes to retract evidence given because it contains a mistake or that witness wishes to change the opinion expressed, a view expressed in a joint expert report should generally be accepted on its face.
74 Secondly, as I have noted, questions of construction are for the Court. In the present case, the proposition that Nalco advances is that Mr Bellwood would not have agreed to the construction I now adopt is because his evidence was that he knew that a product mixture containing only the identified small molecules could not be achieved. Mr Bellwood gave evidence of the technical consequences of a mixture of A + GPS + E at the initial hearing of the case and repeated several times in his evidence on the amendment application, including in the Joint Expert Report. Perhaps more importantly, it is a point that has been made to the Court and has been taken into consideration in construing the claims. However, as I have found, and as Mr Bellwood agreed, the terms of the claim nonetheless include the very construction that Nalco seeks to avoid.
75 Thirdly, the substantive submission advanced by Nalco is that because it is impossible to make a composition consisting only of the small molecules identified in integer (3) of amended claim 1, no person would construe the language of the claim to include such a composition. That proposition assumes that the construction of the claims is to be entirely driven by the technical contribution to the art described in the specification. Such a circular proposition is repugnant to the authorities that require the claims to be understood according to their terms, albeit in the context of the specification as a whole. To distort the plain language of the claim by reference to the technical contribution is to place a gloss on the language of the claim of the type that has long been forbidden; Welch Perrin & Co Pty Ltd v Worrel [1961] HCA 91; (1961) 106 CLR 588 at 610. Furthermore, that submission, and many of the other submissions concerning the construction of the amended claims were substantively advanced before me at the trial of the opposition to the current claims and rejected. I return to this in section 5 below.