High court reaffirms burden of proof in patent infringement

The U.S. Supreme Court ruled unanimously Wednesday the burden of proof of infringement rests with a patent holder even if it wins a declaratory judgment. The case drew considerable interest in the medical device industry. The dispute involved medical devices giant Medtronic Inc. and Mirowski Family Ventures LLC, a private company that owns patents involving implantable heart stimulators. A license agreement allows Medtronic to use several Mirowski patents in exchange for payments. Mirowski alleged Medtronic committed several patent violations and took it to court. A federal judge ruled the patent owner had the burden of proving infringement, and Mirowski had not met that threshold. The U.S. Court of Appeals for the Federal Circuit in Washington, which deals with intellectual property, disagreed, saying though a patent holder normally bears the burden of proof, when a party is the defendant in a declaratory judgment -- such as Mirowski -- then the party seeking the declaratory judgment -- Medtronic -- bears the burden. The U.S. Supreme Court reversed. Writing for the court, Justice Stephen Breyer said in part: "Here, Mirowski set this dispute in motion by accusing Medtronic of infringement, and there is no convincing reason why burden of proof law should favor the patentee. General considerations relating to the public interest in maintaining a well-functioning patent system are, at most, in balance, and do not favor changing the ordinary burden of proof rule."