On May 7, 2015, the California Supreme Court reinstated a claim that an agreement to settle a drug patent infringement dispute violated antitrust laws because (the plaintiffs allege) the patentee in effect paid the infringer not to compete. The court held that an antitrust plaintiff states a prima facie case by showing that the settlement entails the patentee conveying something of value to the alleged infringer; the burden then shifts to the defendants to show that the settlement was pro-competitive. The ruling was a setback for WLF, which filed briefs in support of the defendants. WLF argued that California may not establish a state-law standard any more stringent than the standard adopted by the U.S. Supreme Court under federal law in FTC v. Actavis. WLF argued that any effort by California to impose a more stringent standard is preempted by patent law. The court nonetheless adopted a far more stringent standard, thereby effectively banning all reverse-payment patent settlements.