The Supreme Court of Canada today released the hotly anticipated decision in Teva Canada Limited v Pfizer Canada Inc, 2012 SCC 60 (sildenafil, VIAGRA). In a unanimous decision written by Justice LeBel, the Court found that the patent failed to satisfy the disclosure requirements of the Patent Act.


The ’446 Patent. The patent at issue, Canadian Patent No. 2,163,446 ("’446"), discloses and claims a new use for a class of compounds, namely the treatment of erectile dysfunction ("ED"). In particular, the patent describes:

  • four broad groups of compounds (a general class, "preferred," "more preferred" and "particularly preferred" compounds); and
  • an especially preferred group of nine specifically identified compounds, one of which is sildenafil (the active ingredient in VIAGRA).

While the patent asserts that one especially preferred compound "induces penile erection in impotent males," the patent provides only a summary description of the study and does not identify the specific compound tested or present the data obtained.

The patent claims the new use for various classes of compounds and for the nine especially preferred compounds (as a group). The patent also claims the new use for two compounds individually, including sildenafil (claim 7).

Key statutory provision. Section 27 of the Patent Act is the statutory provision governing disclosure of inventions. The key provision before the Court was section 27(3)(a), which provides:

(3) The specification of an invention must

(a) correctly and fully describe the invention and its operation or use as contemplated by the inventor;

Judicial History

Teva (then Novopharm) alleged that the ’446 patent was invalid, including for inutility and insufficiency of disclosure. In response, Pfizer commenced an application under the Patented Medicines (Notice of Compliance) Regulations ("PMNOC Regulations"). Pfizer succeeded at first instance and on appeal.

Federal Court: 2009 FC 638. Teva's application was dismissed by Justice Kelen, who addressed the inutility and insufficiency issues as follows:

Inutility. Pfizer introduced evidence of a patient study for sildenafil ("Study 350"). Justice Kelen ruled that Study 350 demonstrated utility and that evidence of demonstrated utility was not required to be included in the patent disclosure.

Insufficiency of disclosure. Justice Kelen ruled that the question must be considered for the specific claim in issue. Hence, the Court needed to consider whether the invention of claim 7 was sufficiently disclosed. Justice Kelen found that (i) sildenafil was the only compound in the patent found to induce erections, and (ii) the skilled person would not have known from the specification that the tested compound was sildenafil. However, he found that the skilled person could conduct tests on the two individual compounds claimed and determine which compound worked.

While Justice Kelen rejected the insufficiency allegation, he did so only grudgingly, expressing significant concerns in obiter about the patentee's failure to identify the tested compound:

[136] By withholding from the public the identity of the only compound tested and found to work, sildenafil, the patent did not fully describe the invention. Obviously Pfizer made a conscious choice not to disclose the identity of the only compound found to work, and left the skilled reader guessing. This is contrary to the statutory requirement to fully disclose the invention. [emphasis added]

Federal Court of Appeal: 2010 FCA 242. On appeal, the Federal Court of Appeal upheld the decision of Justice Kelen. The Court agreed that the sufficiency of disclosure should be assessed through the prism of claim 7. The patent was sufficient since it answered the questions posed by the Supreme Court in Consolboard Inc v MacMillan Bloedel, [1981] 1 S.C.R. 504 ("Consolboard"): "What is your invention?" and "How does it work?" The Court also upheld Justice Kelen on the question of utility.

Supreme Court of Canada: 2012 SCC 60. The focus of the decision is whether Pfizer properly disclosed the invention of the ’446 patent. The Court also commented on utility.

Insufficiency of disclosure. The Court stated that "the first step is to define the nature of the invention" in the ’446 patent. The Courts below had treated each claim as a separate invention and therefore considered the disclosure requirements with respect to each individual claim, not to the specification as a whole. The Court rejected the claim-based approach, preferring to consider the specification as a whole. The Court left open the possibility that different claims may disclose separate inventions, but this must be determined on a case-by-case basis.

Turning to the ’446 patent, the Court found only one inventive concept: the use of sildenafil and other compounds in the treatment of ED (i.e. it did not accept that the use of sildenafil was a distinct invention). The Court relied on the following factors:

  • "No specific attributes or characteristics are ascribed to sildenafil that would set it apart from the other compounds."
  • "...nothing ...distinguishes it [sildenafil] from the other eight 'especially preferred compounds.'"
  • "...the patent itself suggests that the entire class of claimed compounds will be effective in treating ED." "The plural word 'inventions' does not appear in Patent '446."

"There is no evidence on the record to suggest that Pfizer filed a divisional application...".

As to whether the disclosure was sufficient, the Court began with Pfizer's actual work (presumably to determine what Pfizer actually invented) before turning to the specification to see whether Pfizer had disclosed that invention.

As Pfizer only conducted tests that demonstrated that sildenafil was effective and none of the other compounds had been shown to be effective, the Court concluded that the invention was the use of sildenafil for the treatment of ED. As the Court noted: "This had to be disclosed in order to meet the requirements set out in s. 27(3) of the Act."

In considering the invention disclosed by the specification, the Court noted that "the specification does not indicate that sildenafil is the effective compound." Further, the disclosure would not enable the public to make the same successful use of the invention as the inventor since, even if a skilled reader could have narrowed the effective compound down to the two compounds that were individually claimed, further testing was necessary to determine which of the compounds actually worked.

In rejecting Pfizer's argument that Teva had been able to make use of the invention having only the specification because it had filed a submission for regulatory approval, the Court stated:

However, this does not change the fact that the specification required, at a minimum, "a minor research project" in order to determine whether Claim 6 or Claim 7 contained the correct compound. The fact that Teva carried out this minor research project is irrelevant to Pfizer's obligation to fully disclose the invention. More importantly, what must be considered is whether a skilled reader having only the specification would have been able to put the invention into practice. The trial judge clearly found that the skilled reader would have had to undertake a minor research project to determine what the true invention was.

The Court found that the courts below misread Consolboard when they stated that the only questions that must be answered are "What is your invention?" and "How does it work?". The Court indicated that these were not the only relevant questions, noting that the description must enable a skilled person to produce the invention using only the instructions contained in the disclosure: "Whether or not a specification is sufficient depends on what a skilled person would consider to be sufficient...".

In concluding that the ’446 patent was insufficient, the Court commented on the practice of cascading claims (broad genus claims that progressively narrow). According to the Court, such claims do not necessarily interfere with the public's right to disclosure since the useful claim is usually the claim at the end for the individual compound. The problem in this case was that the "claims ended with two individually claimed compounds, thereby obscuring the true invention."

The Court provides a stark warning to patentees on the need to make full disclosure:

...Pfizer gained a benefit from the Act — exclusive monopoly rights — while withholding disclosure in spite of its disclosure obligations under the Act. As a matter of policy and sound statutory interpretation, patentees cannot be allowed to "game" the system in this way. This, in my view, is the key issue in this appeal. It must be resolved against Pfizer.

As a result of the failure to properly disclose the invention, the Court ruled that the ’446 patent is invalid and void. This appears to have been an oversight by the Court given that the proceeding arose under the PMNOC Regulations and the only issue was whether the allegation of invalidity was justified. Accordingly, the Court would not appear to have jurisdiction on this appeal to void the patent.

Utility. Teva had argued that claim 7 is invalid for insufficient disclosure of sound prediction. The Court rejected this argument. As the patent stated that the claimed compound will be useful in treating ED and at the time the application was filed sildenafil could assist in treating ED, the Court found that this "is all that is required." The failure to identify the tested compound went to the issue of disclosure of the invention, not to disclosure of the invention's utility. The Court expressly rejected the notion of a separate disclosure requirement for utility under section 27(3).

On the issue of whether an "enhanced" disclosure requirement exists for sound prediction, as has been suggested in decisions of the Federal Court of Appeal, the Court found that sound prediction was not in issue and declined to comment on the question.


While the Court took some care to limit the decision to the peculiar facts of the case, this decision will almost certainly give rise to vigorous challenges by generic drug manufacturers on the basis of insufficiency of disclosure. Perhaps the most troubling aspect of the decision is the Court's emphasis on looking to the disclosure, rather than the issued claims, to divine the nature of the invention.