Heather Hui-Litwin is a J.D. candidate at Osgoode Hall and is taking the Patent Law course.
In patent litigation, claim construction is an extremely important aspect in the analysis of a patent. Findings of infringement and validity ultimately depends on the construction. The leading cases on claim construction is Free World Trust v. Electrosante (2000 SCC 66,  2 S.C.R. 1024) and Whirlpool Corp. v. Camco Inc., (2000 SCC 67,  2 S.C.R. 1067), which upheld the doctrine of “purposive construction”.
In Free World Trust, the court enumerated the proper steps in construing claims, which include, amongst other things, interpreting the patent through the eyes of an ordinary person skilled in the art, prior to any validity and infringement analysis, with regard to the intent of the inventor. Furthermore, in Whirlpool, the court endorsed what Dickson J. said in Consolboard Inc. v. MacMillan Bloedel ((Sask.) Ltd.,  1 S.C.R. 504) that “We must look to the whole of the disclosure and the claims to ascertain the nature of the invention and methods of its performance” (Whirlpool, para. 49)
With the arrival of purposive construction, one wonders if the primacy of claims still hold, as the court held that one must look to the disclosure for meaning of the claims. This raises some anxiety in patent analysis. One used to be able to discern the boundaries of what is claimed in the claims themselves. With purposive construction this does not hold any more! The court tells us to read the patent as a whole, rather than look solely to the claims, to determine what is claimed. Furthermore, this holistic approach would appear to give the patentee flexibility in arguing the exact scope of his claims. It has been argued that claims themselves ought be unambiguous. They should give certainty to the public just what is fenced off. To allow a patentee to rely also on the disclosure is to introduce uncertainty into the claims, which would allow the patentee to claim more than what was in the claims themselves. Are these concerns justified?
When I first read Whirlpool, I was not sure if I liked this new way of construing claims. The case turned on the construction of the word “vanes”. When I read the claim in question, I thought it was clear: the device included “vanes”, which in my mind, not being a person skilled in the art of washing machine manufacture, meant any kind of vane. The expert for the patentee actually testified that at the date of the patent, the only kind of vane contemplated was rigid. Hence, the construction accepted by the court of the word vane by a person skilled in the art is a rigid vane. That, to me, almost seems to be adding in words to the claim itself! Really, when the patentee meant rigid vane, why did they not say so? Surely it is the duty of the patentee to be crystal clear about what it is they are claiming. They should not be allowed to broaden or narrow the claims as they please by being allowed to refer back to the disclosure for further definition of their claims.
Even so, I believe this approach makes more sense than a literal or dictionary approach to claim construction, where the claims themselves are dissected with merciless scrutiny, without context to the patent disclosure. What the court is trying to say, I believe, is that it only makes sense to read any patent as a whole. The English language has inherent weaknesses, such as words that have multiple meanings. (Even the word “construction” has multiple meanings, and of course, in this blog, we are not talking about building houses!) Occasionally the grammar in a claim raises difficulties in interpreting the claims. It only makes sense to read the patent as a whole.
I do not believe it is the court’s intention to give the public extra burden in having to read the whole patent. Nor is it the court’s intention to give unfair flexibility to the patentee in allowing them to claim beyond what is noted in their claims by relying on the disclosure. Rather, the approach is to ensure a fair reading of the patentee’s invention and what he is claiming. An unfair expansion of what is in the claims would be where the claim actually read “rigid vane” explicitly, and yet, the patentee argues that because the disclosure included all shapes and sizes and flexiblities of the vanes, that the claim must be read to include these elements. Binnie J. noted this would not be permitted in FWT (patentee’s own mistake).
The advantage of the purposive approach was clearly demonstrated in a more recent case of Pfizer Canada Inc. v Canada (Minister of Health) (2005 FC 1725). There, the claim was written in such a way as to introduce ambiguity.:
1. An injectable, ready-to-use, sterile, pyrogen-free, anthracycline glycoside solution which consists essentially of a physiologically acceptable salt of an anthracycline glycoside dissolved in a physiologically acceptable aqueous solvent therefore at an anthracycline glycoside concentration of from 0.1 to 50 mg/ml, which has not been reconstituted from a lyophilizate and the pH of which has been adjusted to from 2.5 to 5.0 solely with a physiologically acceptable acid.
Here, there is issue in whether the phrase “which has not been reconstituted from a lyophilizate” refer to solution or the active ingredient. Now, one can see right away that this is a grammatical inquiry. Clearly, the infringing party is engaged in analyzing the actual claim itself in every detail. Justice Hughes notes that this is just the kind of analysis that the court has warned us not to apply. If one had read the whole patent, and asked a person in that field about the active ingredient, one would understand the background to this invention: that is, the patentee has invented a safer way of providing the delivery of the drug, which is highly poisonous, and had always required extremely delicate handling by nurses. The lyophilized active ingredient had always been around, therefore, it makes no sense for the claim to be speaking about the lyophilization to the active ingredient itself. Imagine if the claim was found invalid for ambiguity, which would allow infringers free access to the invention. It is unfair to the inventor, who disclosed to the world in clear terms the details of his invention, only to be deprived of the monopoly of his invention, solely on the basis of technicality of bad grammar of his claim.