Don’t want your patent invalidated? Then you should diligently vet any promissory language in that patent because, as the following cases illustrate, such language raises significant risks of patent invalidation on the basis of inutility under the evolving and controversial promise doctrine in patent law.


On June 13, 2013, Eli Lilly and Company (Eli Lilly) initiated a C$500-million claim against the Government of Canada, alleging that Canada’s patent laws violate the intellectual property standards set out in the North America Free Trade Agreement (NAFTA). While the action was spurred by the challenge to, and consequent invalidation of, two of Eli Lilly’s pharmaceutical patents, the heart of the claim was aimed at use of the “promise doctrine” to invalidate patents in Canadian courts for lacking the level of utility promised in the patent specification. Specifically, Eli Lilly’s notice of arbitration stated that “Canada’s adoption of the promise doctrine was a watershed event in the development of Canada’s intellectual property regime. Not only is Canada applying a utility test that violates the standard required under NAFTA, it is also applying the utility test in a way that discriminates against pharmaceuticals as a field of technology.” While this NAFTA challenge is perhaps the most high-profile case involving the promise doctrine, the doctrine has also been the subject of significant academic debate, several decisions of the Federal Court and Federal Court of Appeal and has even drawn criticism from the United States Trade Representative.


The promise doctrine is often stated to have originated in Consolboard Inc. v. MacMillan Bloedel (Saskatchewan) Ltd., where the Supreme Court of Canada (SCC) defined inutility as meaning “that the invention will not work, either in the sense that it will not operate at all or, more broadly, that it will not do what the specification promises that it will do” [emphasis added]. In other words, if a patent makes a promise as to the utility of the invention, the patentee will be held to that promise, meaning that the patentee will be required to have demonstrated or soundly predicted that promised utility as of the filing date of its application. In contrast, if a patent makes no promises, then a “mere scintilla” of utility is sufficient to preserve its utility.


Recent decisions have clarified two important aspects of the promise doctrine:

  1. A mere "goal" falls below the threshold of an enforceable promise
  2. An enforceable promise can be found outside of a patent's claims 

Not Every Goal is an Enforceable Promise

Recent decisions have clarified that a mere reference to the goals of a patent falls below the threshold of an express promise.

For example, in Pfizer Canada Inc. v. Apotex Inc., Justice S. Harrington of the Federal Court held that the patent at issue (for the drug Celebrex) contained only a goal of use as an anti-inflammatory agent in humans, not a promise of such. Justice Harrington reached this conclusion after considering multiple aspects of the patent which, in his view, weighed against the patent providing such an express promise, including: (1) that the patent only referred to treating a “subject”, a term that does not necessarily imply use in humans; and (2) that the utility of the patent was demonstrated in tests using rats, suggesting that the patent only promised use in rats. Justice Harrington's rejection of a promise of use in humans in the Celebrex patent was upheld by the Federal Court of Appeal

Similarly, in AstraZeneca Canada Inc. v. Apotex Inc. (Apotex), Justice Rennie (now of the Federal Court of Appeal) affirmed and clarified the difference between patent goals and promises. Specifically, Justice Rennie clarified that promises are different from goals because promises are “explicit and define guaranteed or anticipated results of the patent […] whereas goals merely relate to potential uses for the patent.” With respect to the patent before him, Justice Rennie held that it promised compounds with an improved therapeutic profile because it stated that it “will” (not "may") provide such compounds. Justice Rennie's promise analysis was recently upheld by the Federal Court of Appeal

Promises Can Be Found Outside of a Patent's Claims 

Recent decisions have also held that a patent's promise may be found outside of its claims.

In Apotex, the promise identified by Justice Rennie was found outside of the patent's claims, though Justice Rennie's conclusion was reached after a consideration of the patent as a whole.  

Most recently, in Eli Lilly Canada Inc. v. Mylan Pharmaceuticals ULC, Justice de Montigny held that if a patent’s claims “clearly and unequivocally” set out a promise, this should be taken as the promise of the patent. However, Justice de Montigny also clarified that if the promise is not clearly expressed in the patent’s claims, a promise may be found outside of the claims, and that, in any event, the promise should be construed within the context of the patent as a whole. Indeed, despite his emphasis on the claims when construing a patent's promise, Justice de Montigny ultimately found a promise in the patent for the drug Cialis outside the claims and invalidated the patent for failing to demonstrate or soundly predict that promise. 


The promise doctrine has faced criticism for imposing a subjective utility standard that is arbitrary and unpredictable (see Norman Siebrasse, “The False Doctrine of False Promise,” (2013) 29(1) Canadian Intellectual Property Review 3). Although some recent jurisprudence has reduced this uncertainty by establishing an analytical framework around the interpretation of patent promises (e.g. the delineation between goals and promises), much work remains to be done. 

The promise doctrine has also faced criticism for invalidating patents, on the basis of lack of utility, despite the fact that the inventions at issue actually had a high degree of utility. Others, in responding to this criticism, have argued, like Justice Rennie in Apotex, that constraining innovators from over-promising is a reasonable approach to preserving the core policy objectives of patent law “which serve to create consistency and clarity in the bargain struck between innovators and the public.” 

The Federal Court of Appeal’s decision in Apotex is the subject of an application for leave to appeal to the SCC. The SCC’s guidance on the promise doctrine would bring some much-needed clarity to Canadian patent law. In the meantime, innovators should diligently vet any promissory language in their patents, whether or not that language is located in their patents' claims, because, as the foregoing cases illustrate, such language raises significant risks of patent invalidation on the basis of inutility.