On June 17, 2013, the U.S. Supreme Court reversed an appeals court’s ruling which held that a routine agreement to settle a patent dispute does not violate federal antitrust law. In a 5-3 decision, the Supreme Court held that if a patent holder settles patent litigation by paying an alleged infringer a “large and unjustified” payment in exchange for the alleged infringer’s agreement to honor the patent, a court should employ the antitrust rule of reason to determine whether the settlement violates antitrust law. In announcing this rule, the Court rejected the per se rule advanced by the Government, which would have deemed all such settlement agreements presumptively unlawful. The decision was a partial victory for the Washington Legal Foundation (WLF), which had filed a brief in the case urging the Court to reject the per se standard advanced by the Government. In its brief, WLF argued that such a rule would deprive the holders of drug patents of critically important legal rights.