Court Explores Subtle Choice of Law Issue in Patent Litigation

June 14, 2006

Federal courts apply federal privilege law in federal question cases, and state privilege law in diversity cases. Patent cases present a more complicated choice of law issue, because the Federal Circuit applies (1) its own law to patent issues and (2) regional circuit law to non-patent procedural issues.

In MPT, Inc. v. Marathon Labels, Inc., No. 1:04 CV 2357, 2006 U.S. Dist. LEXIS 4998, at *8 (N.D. Ohio Feb. 9, 2006), the court applied this basic principle — concluding that “the existence of the privilege will be determined by Federal Circuit law while waiver and the community of interest doctrine [usually called the “common interest” or “joint defense” doctrine] will be decided by Sixth Circuit law.”

Lawyers litigating patent cases should be prepared to deal with these and other subtleties.