In Hall St. Assocs., L.L.C. v. Mattel, Inc., 552 U.S. 576 (2008), petitioner Hall Street Associates, L.L.C., and respondent Mattel, Inc., initiated litigation in the United States District Court for the District of Oregon, but soon reached an impasse on the parties' indemnification portion of the dispute. The parties offered to submit to arbitration and the District Court was amenable. As a result, the parties drafted an arbitration agreement, approved by the District Court and entered as an order, providing the District Court with the authority to vacate, modify, or correct any award where the arbitrator's findings of fact were not supported by substantial evidence or where the conclusions of law were erroneous. Hall St., 552 U.S. at 579. Arbitration proceedings took place and the arbitrator ruled that Mattel was not obligated to indemnify Hall Street. Hall Street subsequently filed a motion to vacate, modify, or correct the arbitration decision on the ground that the arbitrator's decision constituted legal error. The District Court vacated the award based on the standard of review provided in the parties' contractual agreement. Id. at 580. After the arbitration decision was revised on remand, each party sought modification in the District Court, which largely upheld the award pursuant to the same standard of review provided in the parties' agreement. On appeal to the Ninth Circuit Court of Appeals, Mattel argued that the arbitration agreement's provision for judicial review of legal error was unenforceable. The Ninth Circuit reversed in favor of Mattel, instructing the District Court to consider the original decision of the arbitrator pursuant to the grounds allowable under 9 U.S.C. 10, or modified or corrected under 9 U.S.C. 11. After the District Court again held for Hall Street, reasoning that the arbitration award rested on an implausible interpretation of the lease and thus exceeded the arbitrator's powers, the Ninth Circuit reversed, holding that implausibility is not a valid basis for vacatur. Thus, the Supreme Court granted certiorari review to consider whether the grounds for vacatur and modification provided by 10 and 11 of the FAA are exclusive or whether the statutory grounds may be supplemented by contract. Id. at 581.