First it was the metric system—now it’s the patent law. We’re heading on a very different course in Canadian patent law from our cousins south of the border.
Patents protect technology and the way technology works. The monopoly of a patent is defined by the claims of the patent—what should be a checklist of elements or steps. The Patent Act requires you to write "distinctly and in explicit terms" the thing or combination of things that is new. In effect, the Patent Act requires an inventor to claim only what is essential to the invention. The patent owner, subject to objections raised by the Patent Office, is the author of the checklist. He or she writes the claims with as many or as few words as he or she wishes.
In theory, if someone else has what is contained in the checklist, that person is infringing the patent. If you put more in the checklist, more should be needed to infringe. Thus, if you put less in the checklist (while still being inventively different from what everyone else has already done), less should be needed to infringe, or put another way, the broader your patent protection.
There has been an inherent contradiction in claim construction for some time: are the words of a claim all of equal importance, or can the court rewrite the claim, dropping or modifying elements? If it can consider some elements to be less important and variable, to what extent can the words or actions of the patent owner limit or expand the scope of the patent? Can the patent owner or inventor make admissions against interest and be held to them at trial?
Recent U.S. cases have swung towards a stricter interpretation of the claim language, limiting the scope of the patent to precisely the elements the patent owner claimed and, in limited cases, to equivalents of those elements. As in the TV show Dragnet, anything a patent owner says while trying to get his or her patent can and will be used against him or her in a U.S. court.
Doctrine of Equivalents
Under U.S. law, a patent claim is infringed by anyone who, without permission, makes or sells a device or uses a method that has all the elements of the claim, or their equivalents. The U.S. doctrine of equivalents provides that if the claim says that two things are attached by a screwnail, then any fastener that performs the same function (fastening) in the same way (by mechanical attachment) constitutes an infringement of the patent.
U.S. Supreme Court
In Warner-Jenkinson, the U.S. Supreme Court held that, in order for there to be infringement of a patent, the infringing device must have all the elements of the claim or equivalents of all the elements. If an element or its equivalent is completely missing, there is no infringement (an "all-elements" test).
If a patent applicant amended the words in the proposed claim in response to a request from the patent examiner, limiting the element from something broad and general to something narrower, then equivalents would not infringe that patent. To do otherwise would expand the scope of what had already been limited. That would be unfair to the public, who, through the Patent Office, negotiated the granting of the patent with the narrower element.
The most recent U.S. decision, Festo, held that if the claims were amended during the application phase for any reason, equivalents would not infringe that patent. Once a claim element was narrowed during the application phase, it could not be interpreted to include equivalents after the patent was granted. The Festo decision has surprised and frightened many U.S. practitioners whose clients made voluntary amendments and may now not be able to make use of the doctrine of equivalents. Festo is not popular among patent owners, but provides increased predictability and clarity as to the scope of U.S. patents, making it easier for competitors to figure out how to avoid infringement.
Supreme Court of Canada
In contrast, two recent Supreme Court of Canada decisions, Free World and Whirlpool explicitly endorsed what appear to be two mutually contradictory claim construction approaches and require the courts to ignore admissions against interest made during the application phase.
On the one hand, the court in Whirlpool and Free World seemed to adopt an "all-elements" literal construction approach, analogous to the U.S. Warner-Jenkinson case, when it said: "The Patent Act promotes adherence to the language of the claims..." which "...in turn promotes both fairness and predictability," and commented favourably on a Federal Court of Appeal decision that said that "a court must interpret the claims; it cannot redraft them."
But the court then endorsed an approach that constituted rewriting the patent by categorizing the claim elements into "essential" and "inessential" elements, the latter of which could be varied (analogous to the U.S. doctrine of equivalents) or completely ignored (contrary to an "all elements" approach).
What if the patent owner said, during the negotiation with the Patent Office, that a certain element was essential to the invention, to make it new and inventive over what had gone on before ("the prior art")? Would that sort of statement be seen to be an admission against interest, with the patent owner then being estopped from arguing at trial, after being given the patent based in part on that admission, that the same element was now inessential and could be modified or ignored? In the U.S.A., correct; in Canada, Free World says that you cannot consider such prior admissions when interpreting the patent. While Canadian law of contract interpretation and constitutional law increasingly allow parol evidence to determine the intention of the contracting parties or the intent of the legislation, Free World went the opposite way with patents.
So, in the future, will Canadian courts hold patent owners to the language of the claims as a person who works in that art would read the claims, or will they give claim language leeway, allow equivalents and ignore claim elements? The answer appears to be unequivocally "Yes."
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