“A patentee ordinarily bears the burden of proving infringement. This case asks us to decide whether the burden of proof shifts when the patentee is a defendant in a declaratory judgment action, and the plaintiff (the potential infringer) seeks a judgment that he does not infringe the patent.”
“[W]hen a licensee seeks a declaratory judgment against a patentee to establish that there is no infringement, the burden of proving infringement remains with the patentee.”
