Is the sildenafil patent invalid?

In a decision released today, Justice Zinn held that the Federal Court had jurisdiction to consider Apotex’s impeachment action and motion for summary judgment and declared Pfizer’s patent on Viagra, Canadian Patent No. 2,163,466 invalid.

The decision was in Apotex’s impeachment proceeding, T-772-09, Apotex Inc. v. Pfizer Ireland Pharmaceuticals, 2012 FC 1339 (PDF).

Earlier this month, the Supreme Court determined in Teva Canada Ltd. v. Pfizer Canada Inc.2012 SCC 60, that Patent No. 2,163,446 (PDF), Pfizer’s patent on sildenafil the active ingredient in Viagra had an insufficient disclosure and was therefore invalid.

As noted in my summary of the Supreme Court’s decision, the Court held the patent invalid even though in a PM(NOC) proceeding, a court normally only determinines if the allegations of invalidity and non-infringement are justified. Pfizer has now sought a reconsideration/rehearing of the declaration of invalidity.

In a parallel proceeding, Apotex brought an impeachment action on the same patent, scheduled to go to trial next week in T-772-09. In view of the Supreme Court’s decision, both Apotex and Pfizer brought motions for summary judgment: Apotex sought declaration that the patent was invalid in view of the Supreme Court’s ruling while Pfizer sought dismissal of the impeachment action on the basis that the court lacked jurisdiction in view of the Supreme Court’s ruling. Both parties are likely trying to position themselves favourably for a costs award.

In today’s ruling, Justice Zinn dismissed Pfizer’s motion for lack of jurisdiction saying “this Court retains jurisdiction to hear this action notwithstanding the declaration of invalidity of the ‘446 Patent by the Supreme Court.” (para 23) If the Supreme Court does reconsider its ruling as requested by Pfizer then the declaration of invalidity was a nullity (para 19). The court also refused to dismiss the action for mootness:

[28] I accept that as things currently stand, this action is moot. Apotex has been granted its NOC and the Supreme Court has declared the ‘446 Patent void. Apotex has all that it seeks in this action, save its costs. However, Pfizer’s motion to the Supreme Court, like the sword of Damocles, hangs over the head of Apotex. Pfizer does not concede that Apotex is and will remain at liberty to produce and market its generic version of Viagra with no fear of suit from Pfizer. It is fair to say, given Pfizer’s submissions on these motions, that the possibility of an action for infringement if the Supreme Court amends its Judgment and removes the declaration of invalidity is not unlikely. That alone, in my view, is sufficient reason not to dismiss the action now for mootness. …

With regards to Apotex’s motion, the Court held that the Supreme Court made a binding legal determination dispositive of the impeachment action (para 30) as construction of a patent is a matter of law.

[32] I reject the submission of Pfizer that the question of the sufficiency of disclosure in Teva was a mixed question of fact and law. I agree with Apotex that in Teva the sufficiency of the disclosure of the ‘446 Patent turned on three questions of law: (1) the determination of the invention or inventive concept of the patent, (2) the construction of the ‘446 Patent, and (3) whether the ‘446 Patent, properly construed, permitted the person of skill in the art “to make the same successful use of the invention as the inventor could at the time of his application.”
[33]    The determinations made by the Supreme Court on those three questions of law are binding on this Court. Its finding that Pfizer, in failing to disclose which of the many compounds named in the ‘446 Patent was effective in treating erectile dysfunction, had not properly or sufficiently disclosed its invention, is a finding that this Court must respect and follow. As a consequence, when, as here, the action seeks a declaration of the invalidity of the ‘446 Patent for insufficient disclosure, there can be no genuine issue for trial because no result is possible other than a finding that the ‘446 Patent is invalid. Accordingly, Apotex is entitled to summary judgment.

Justice Zinn granted Apotex its costs on the action and the motions. Watch for possible appeals to the Federal Court of Appeal.

[Updated to include quotes from decision and on potential consequences.]