Prior Use Defense Raised Too Late In Infringement Case

Akin Gump attorneys Karina J. Moy, Jason Weil, and Rubén H. Muñoz analyze a patent infringement case in which a district court granted the plaintiff’s request to strike the defendant’s prior use defense under 35 U.S.C. § 273. The statute provides a defense based on prior commercial use of the claimed product. The issue here was when that defense was raised.

The court first granted the plaintiff’s motion for summary judgment. Then the defendant raised a prior use defense, and the plaintiff filed an ex parte request to strike it as untimely.

The plaintiff argued that the defendant didn’t mention prior use until just before the pretrial conference when it filed its pretrial Memorandum of Contentions of Fact and Law. The defendant responded that it had previously pleaded facts consistent with a prior use defense.

The court held that the defendant couldn’t rely on background facts consistent with a prior use defense to establish that it had been raised in a timely way. It noted that the statutory language suggests that the defense must be actually pleaded. 

The court also granted in part the plaintiff’s motion to exclude the defendant’s arguments and evidence comparing its own products to prior art devices. The defendant argued that the comparisons were relevant to the infringement claims, as well as the prior use defense. The court ruled that the evidence was irrelevant to infringement.

It did, however, refuse to exclude the arguments and evidence of prior use for the sole purpose of potentially rebutting willful infringement arguments by showing a good faith belief that the asserted patents were invalid. 

The Akin Gump attorneys say that a prior use defense can be useful, for example, if an infringement is not contested, but it should be raised expressly in the pleadings.