Plead It Or Lose It: Prior Art And Expert Evidence

Expert evidence and prior art (e.g., earlier publications showing the invention was already known) drive nearly every patent dispute. A recent trilogy of interlocutory decisions from the Federal Court shows the pleadings and the burden of proof decide which of that evidence reaches the trial judge. For parties attacking validity, the message is blunt: plead it or lose it.

Salix Pharmaceuticals, Inc. (Salix) brought an action against Sandoz Canada Inc. (Sandoz) under the Patented Medicines (Notice of Compliance) Regulations concerning the antibiotic rifaximin. After discovery, Sandoz proposed extensive amendments to its defence and counterclaim, including new invalidity grounds and additional prior art references. Cautioned by the Court that a contested amendment motion would likely jeopardize the trial date, Sandoz chose not to formally move to amend and instead made only the amendments Salix accepted.