Purposive Claim Construction: Settled Law with Unsettled Application

Essien Udokang is a J.D. Candidate 2010 at Osgoode Hall and is taking the Patent Law class.

Since the decision of the Supreme Court in Free World (2000 SCC 66, [2000] 2 S.C.R. 1024) it is supposedly settled law that courts are to construe the claims of a patent in a purposive manner in determining infringement and invalidity. However, courts since Free World have failed to demonstrate consistency in their application of purposive claim construction. What appears from the existing case law is a disparate collection of decisions that fuels litigation and consumes judicial resources. Some courts have kept tightly wed to claims, while others have liberally given more weight to non-claim material, even to the point of disregarding relevant claims and implying promises from the patent’s overall context. Subsequently, stakeholders are subjected to an unpredictable legal landscape with unfortunate consequences.

Firstly, the patentee is no longer confident that his invention will remain protected; a patentee can no longer read his own claims with the belief that the protection he negotiated in prosecution is that which the court will impute. Secondly, the patent system is unreasonably burdened, as competitors are encouraged to infringe patents comforted by knowing they can bring actions for invalidity premised on allegations sourced in the confusion generated by stepping outside the claims. Thirdly, the public policy purposes of maximizing certainty and predictability are compromised since one reading a patent’s claims cannot say for sure that his actions will be infringing on the patentee’s right, and so further innovative efforts are discouraged.

Ludlow and Godbout articulate the importance of accurate claim construction: “…If the boundaries of a patented invention cannot be ascertained ‘with some measure of exactness’ there is risk that others will stray across the line or be discouraged from seeking new or better inventions.’” (Unilever PLC v. Procter & Gamble Inc. (1995), 61 C.P.R. (3d) 499 (F.C.A.), aff’g (1993) 47 C.P.R. (3d) 479 (F.C.T.D.), cited in Gregory C. Ludlow & Anne M. Godbout, “Survey of Intellectual Property Part IV – Patents” (1998-1999) 30 Ottawa L. Rev. 117 at para. 104). It seems that the court should be more strictly wedded to claims and far less inclined to step outside of these claims to import ‘peripheral meaning’ for the purpose of gleaning the patentee’s intention. I am not advocating a return to literal claim construction, even where a claim is apparently plain and unambiguous; indeed, it is “often unsafe to conclude that a term in a claim [is] plain and unambiguous without having carefully reviewed the specification.” (J.F. Anderson, Patent Law of Canada (Scarborough: Carswell, 1994) at 190, cited in Pfizer Canada Inc. v. Canada (Minister of Health), 2007 FCA 209, [2007] F.C.J. No. 767 at para. 88).

One example of the confusion in the law can be found in the case of Pfizer Canada Inc. v. Canada (Minister of Health) (2005 FC 1205). Heneghan J. of the federal trial court examined the utility of claims that covered quinapril. Pfizer argued that a purposive construction would lead to a finding that the ‘330 patent disclosed an invention relating to ACE inhibition. Conversely, Apotex argued that the invention only encompassed a smaller group of compounds useful in relieving hypertension and not a broader group of ACE inhibitors, some of which did not have sufficient activity to be useful in treating hypertension. Apotex argued that the disclosure limited the invention to those stereoisomers with an “S-configuration”, which was known to be especially effective at treating hypertension, but that claims 3 and 5 included all stereoisomers and therefore were overly broad. The trial judge construed claims 3 and 5 of the ‘330 patent, but failed to include claim 1 of the related ‘615 patent in her analysis, pre-determining, in effect, that it was not essential. Yet the issue of infringement “depend[ed] entirely on the construction of claim 1,” (Pfizer, 2007 FCA 209, at para. 43) since it included biochemical configurations that were covered by the ‘330 patent and that a skilled person would consider to include the drug Apotex sought to manufacture.

Heneghan J. concluded that since “claims three (3) and five (5) should be construed so as to include [all] compounds useful for reducing hypertension and [a sub-set of those compounds,] the S-configuration[,] is the optimal configuration for high level ACE inhibition leading to anti-hypertensive results, … the claims … are overly broad” (Pfizer, ibid. at para. 114). In reversing the trial court’s decision, Nadon J.A. of the Federal Appeal Court insisted that, by failing to thoroughly adhere to the claims in her construction analysis, Heneghan J. did not gain the most accurate understanding of the ambit of protection to be afforded to Pfizer, and would have incorrectly allowed Apotex to infringe Pfizer’s patent. In making reference to the disclosure, which referred to the use of the invention for the treatment of hypertension, Heneghan J. determined that the relevant claims would be read as referring to compounds useful for the relief of hypertension, and not more generally useful in ACE inhibition. Yet claims 3 and 5 claimed “‘all possible stereoisomers’ of the family of claimed compounds,” which were useful in ACE inhibition, and claim 1 included the infringed compound (Pfizer, ibid. at paras. 120 and 121). Importantly, also, Pfizer had not claimed use for treatment in hypertension. As such, Heneghan J. imported a therapeutic promise from the disclosure, which was not asserted in the claims. This case illustrates the dangers in a more liberal application of purposive claim construction.

By clearly demarcating the boundary of rights afforded by a patent, through stricter adherence to its claims, the court better serves the balanced interests of all stakeholders. With the current state of purposive construction members of the public cannot adequately demark the scope of protection afforded by a patent, and so are discouraged from undertaking related advancements in research. First innovators are also forced to direct more resources into legally defining and protecting those boundaries. Increased costs are then transferred to the consumer. Ultimately, the public – who is supposed to benefit – suffers.