The Supreme Court of the United States ruled that the patent holder has to shoulder the burden to prove infringement by a potential infringer, in a declaratory judgement. This is against the current practice in the USA, where the patent holder merely claims that the potential infringer is infringing on one or more of its patents. The potential infringer has to compare his process/product with the patent(s) of the patent holder and evaluate whether the product/process is infringing on the patent(s). Based on this evaluation, the potential infringer would have to prove the same in a court of law, while the patent holder has to merely disprove the arguments of the potential infringer, without having to actually prove that the product/process actually infringes the patent(s) of the patent holder.
Case in point is Medtronic, Inc vs. Mirowski Family Ventures, which had passed through the lower courts. The Federal Circuit had ruled that the burden of proof was on the potential infringer (Medtronic) and not on the patent holder (Mirowski), overruling the judgement of the lower court which had ruled that the patent holder had to prove infringement. The Supreme Court of the United States, in a 9-0 decision, overturned this decision of the Federal Circuit, putting the burden of proof back on the patent holder.
Previously, Medtronic was licensing Mirowski’s patents related to implanted heart stimulators. The agreement between Medtronic and Mirowski included a clause that stated that if a new Medtronic patent claimed to be infringing a Mirowski patent, then Medtronic may pay royalty, either directly or via an escrow account, while pursuing a declaratory judgement. Mirowski claimed that 7 new Medtronic products infringed 2 patents held by Mirowski. Medtronic pursued a declaratory judgement in the Federal District Court of Delaware. The District Court ruled that, as Mirowski was asserting infringement, the burden was on Mirowski to prove the infringement, which was reiterated by the Supreme Court of the United States.