“In this case, we address whether the Court of Appeals for the Federal Circuit has appellate jurisdiction over a case in which the complaint does not allege a claim arising under federal patent law, but the answer contains a patent-law counterclaim.”
“Not all cases involving a patent-law claim fall within the Federal Circuit’s jurisdiction. By limiting the Federal Circuit’s jurisdiction to cases in which district courts would have jurisdiction under [28 U.S.C.] ยง 1338, Congress referred to a well-established body of law that requires courts to consider whether a patent-law claim appears on the face of the plaintiff’s well-pleaded complaint.”
