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Clarification of the “promise” of utility doctrine in Canada

In a decision dated October 30 2014, the Federal Court of Appeal provided some clarification on the utility requirements for patentability in Canada, and in particular the nature and application of the "promise" of utility. This doctrine has recently been extensively relied on by generic companies in their attempts to challenge the validity of pharmaceutical patents to gain market entry prior to patent expiry.

The decision deals with appeals by Apotex and Mylan in separate cases under the Patented Medicines (Notice of Compliance) Regulations, in which the Federal Court prohibited the Minister of Health from issuing marketing approval (a notice of compliance) to each generic for celecoxib (Pfizer's CELEBREX).

The main issue in both appeals was whether the Federal Court judge properly held that patent No. 2,177,576 (576), did not promise certain specified results and consequently correctly declined to find that the generics' allegations of invalidity were justified by reason of the patent's alleged failure to provide these results.

Background and the 576 Patent

The background to the invention included the fact that non-steroidal anti-inflammatory drugs (NSAIDs) reduce inflammation by inhibiting an enzyme called cyclooxygenase (COX). However, NSAIDs can have dangerous side effects in the long-run, particularly in the gastrointestinal tract, where bleeding, ulcers and perforations can take place. Researchers subsequently discovered that there exist two different COX enzymes and hypothesized that, while COX-1 plays a general maintenance role in many tissues, the body produces COX-2 in response to injury and it is this enzyme that causes inflammation. NSAID researchers hypothesized that, if one could develop a drug that either selectively inhibited COX-2 exclusively or at least inhibited COX-2 significantly more than it did COX-1, then that drug could reduce inflammation without producing the sort of side effects associated with the NSAIDs on the market at the time.

Claim 4 of the 576 patent claimed the compound celecoxib; claim 8 claimed a therapeutically-effective amount of celecoxib; claims 9 to 13 claimed the use of celecoxib to treat inflammation and other specified conditions or disorders in a "subject"; and claim 16 was directed at the prevention of colorectal cancer in a "subject".

In the description section, the 576 patent stated "The compounds are useful as anti-inflammatory agents, such as for the treatment of arthritis, with the additional benefit of having significantly less harmful side effects. The present invention preferably includes compounds which selectively inhibit [COX-2 over COX-1]….Such preferred selectivity may indicate an ability to reduce the incidence of common NSAID-induced side effects".

Federal Court

Before the Federal Court judge, the generics, relying on the "are useful as" language in the description, argued that the 576 patent was invalid as it promised reduced side effects in humans, which celecoxib did not provide. Apotex additionally argued that the patent promised utility in humans as an anti-inflammatory and for preventing colorectal cancer, which was neither demonstrated nor soundly predicted as of the filing date. The judge however accepted Pfizer's submission that the word "may" in the description merely contemplated the possibility of reduced side effects and the claims themselves did not mention reduced side effects. The judge also found that the reference to "subjects" in the claims could be to rats and hence did not promise utility in humans.

Federal Court of Appeal (FCA)

On appeal, the FCA addressed the generics' distinct arguments of a lack of utility: (1) in treating inflammation in humans; (2) in reducing side effects; and (3) in preventing colorectal cancer.

The FCA first commented on the Patent Act basis for the utility requirement and noted that the minimum requirements for utility are "fairly forgiving" and the threshold "is generally quite low".

[64] Under the Act, an invention must be useful in order to deserve protection (s. 2). The courts, however, have long held that the minimum requirements for utility under the Act are fairly forgiving. First, the inventor need not expressly set out the utility of the invention in the patent (Consolboard Inc. v. MacMillan Bloedel (Saskatchewan) Ltd., [1981] 1 S.C.R. 504 at 525 and 526 [Consolboard]. It is merely required that, where the inventor is called upon to prove the utility of the invention, utility can be shown to be demonstrated or soundly predicted as of the patent's filing date (AZT). Second, the threshold that must be proven to establish utility is generally quite low, described as being no more than a "scintilla of utility" (Olanzapine).

The FCA explained that the promise doctrine is an exception to the minimum utility requirements where a patent provides a clear, unambiguous and explicit promise of a specific result.

[65] The promise doctrine represents an exception to the above minimum statutory requirements. Though an inventor need not describe any particular utility for the invention, an inventor who explicitly promises a specific result will be held to that promise when called upon to prove utility…. That the invention may well have satisfied the scintilla threshold is of no assistance in establishing utility where a promise, if it be made, cannot be met…...

[66] The promise doctrine will hold an inventor to an elevated standard only where a clear and unambiguous promise has been made. Where the validity of a patent is challenged on the basis of an alleged unfulfilled promise, the patent will be construed in favour of the patentee where it can reasonably be read by the skilled person as excluding this promise. This approach can be traced back to the earliest mentions of the promise doctrine. In Consolboard, the source of the promise doctrine in Canadian law, the Supreme Court of Canada reiterated the longstanding principle that…..:

…where the language of the specification, upon a reasonable view of it, can be so read as to afford the inventor protection for that which he has actually in good faith invented, the court, as a rule, will endeavour to give effect to that construction.

[67] This rule in favour of saving an invention rather than invalidating it in case of ambiguity has been consistently applied by this Court….

Utility in Treating Inflammation in Humans

The FCA accepted that "when a result or advantage is asserted in a patent's claims, it will generally be seen as a promise of utility". However, the claims speak only of "subjects", and there was no unequivocal language outside the claims that could support the promise of the patent extending to humans.

Utility in Reducing Side Effects

The FCA stated "statements outside of the claim should not be presumed to be promises", in concluding that the Federal Court judge did not err in not finding a promise of reduced side effects.

Utility in Preventing Colorectal Cancer

On this issue, while the FCA accepted that "some promises may impose utility requirements across each of a patent's claim[s]", it rejected Apotex's argument that "any given promise made in a patent must be construed as overarching to the invention and all of the patent's claims". The 576 patent had claims to compounds and claims to uses. Any promise of preventing colorectal cancer was limited to claim 16. The issue of the extent to which a promise applies to various different claims "is one of patent construction". Consequently, any utility promised for claim 16 which rendered it invalid should not affect the validity of other claims which did not promise such a utility.


This FCA decision is important in providing some helpful clarification, to the benefit of patentees, on the correct approach for determining whether a heightened or elevated utility has been promised in a patent. The correct approach appears to be one of individual claim construction. Statements going to utility are particularly vulnerable to being read as a promise when they are expressed in a patent's claims. However statements made outside the claims should not be presumed to be a promise, but they may be, if explicit, clear and unambiguous. But even then, such a promise does not necessarily apply to all the claims. The utility requirement for patentability is forgiving, generally a quite low threshold ("a scintilla") and in the case of ambiguity, the rule in favour of saving an invention rather than invalidating it should be applied. It is noted that both generics have sought leave to appeal the decision (Apotex, Mylan v. Pfizer, 2014FCA250) to the Supreme Court of Canada.