A Department of Justice criminal investigation revealed that Stolt (D) was engaging in an illegal price-fixing conspiracy. When AnimalFeeds (P) learned of this, it brought a putative class action against Ds asserting antitrust claims for supra-competitive prices that petitioners allegedly charged their customers over a period of several years. The Judicial Panel on Multidistrict Litigation ordered the consolidation of then-pending actions against Ds, including P's action, in the District of Connecticut. P served Ds with a demand for class arbitration, designating New York City as the place of arbitration. The parties entered into a supplemental agreement providing for the question of class arbitration to be submitted to a panel of three arbitrators. The parties selected a panel of arbitrators and stipulated that the arbitration clause was “silent” with respect to class arbitration. The arbitrators concluded that the arbitration clause allowed for class arbitration. The arbitrators stayed the proceeding to allow the parties to seek judicial review, and Ds filed an application to vacate the arbitrators’ award. The District Court vacated the award, concluding that the arbitrators’ decision was made in “manifest disregard” of the law insofar as the arbitrators failed to conduct a choice-of-law analysis. P appealed to the Court of Appeals, which reversed. The Supreme Court granted certiorari.