Prosecution History Cannot Be Invoked Against Patent Licensees

• Published date: 13 January 2021
• Subject Matter: Intellectual Property, Real Estate and Construction, Patent, Construction & Planning
• Law Firm: Norton Rose Fulbright Canada LLP
• Author: Mr Fortunat Nadima Nadima, Christopher Guerreiro and Brian R. Daley

The Federal Court has found that prosecution history evidence is inadmissible to rebut representations made by a patent licensee (as opposed to the patentee) on claims construction. The Court also considered the issues of "essential elements", infringement, and obviousness in the context of a formulation patent.

Background

The Court's decision concerns Canadian Patent No. 2,507,002 (002 Patent), which is listed on the patent register against Allergan Inc.'s (Allergan) silodosin capsules (marketed as RAPAFLO^') under an exclusive license in Canada granted by Kissei Pharmaceutical Co., Ltd. (Kissei). Allergan brought an action against Sandoz Canada Inc. (Sandoz) under subsection 6(1) of the Patented Medicines (Notice of Compliance) Regulations (Regulations) seeking a declaration that Sandoz's generic alternative to RAPAFLO^' would infringe claims 1-3 and 6 of the 002 Patent. Sandoz denied infringement and counterclaimed for a declaration that the 002 Patent was invalid for obviousness. Kissei, the patentee, denied invalidity but took no position on infringement.

The claims of the 002 Patent related to capsules comprising the active ingredient silodosin (used for the treatment of dysuria) and specific excipients, manufactured so as to achieve a defined rapid dissolution profile.

Claims valid but not infringed

The Court found against Allergan on the issues of claims construction and infringement, but rejected Sandoz's invalidity counterclaim.

The crux of the claims construction issue was whether claim elements relating to wet granulation-a manufacturing process that Sandoz did not use-were essential. The Court concluded that Allergan had failed to meet its burden of proving that these claim elements were non-essential. This finding was supported by a purposive construction of the claims and the 002 Patent specification as a whole, which taught "away from the use of a dry manufacturing process and towards the wet granulation process". The Court accepted that "the Skilled Person would not have understood that a dry process could be substituted for the wet granulation process without materially affecting the working of the invention". As discussed in greater detail below, the Court refused to consider the prosecution history of the patent in reaching its conclusion.

Following from its finding on claims construction, the Court concluded that Sandoz's product would not infringe claims 1-3 or 6 of the 002 Patent: it was agreed that the product did not contain...