By Preston Ratliff, Edwin Mok and Carl Minniti ( April 17, 2018, 12:21 PM EDT) -- On April 13, 2018, the Federal Circuit held that a Hatch-Waxman plaintiff's patent claims concerning methods of treating schizophrenia were not directed to a patent-ineligible concept under step one of the U.S. Supreme Court's Mayo test,[1] and thus eligible subject matter under § 101 of the Patent Act. The majority opinion in Vanda Pharmaceuticals Inc. v. West-Ward Pharmaceuticals International Limited,[2] written by Judge Alan Lourie and joined by Judge Todd Hughes, is the first Federal Circuit opinion to directly speak to the patent eligibility of method-of-treatment claims under the Mayo two-step framework, and builds on the court's decision in Rapid Litigation Management Ltd. v. CellzDirect Inc.,[3] in embracing the importance of step one of the Mayo test....