In disputes involving a multi-staged dispute resolution process, the arbitrator, not a court, determines whether a precondition to arbitration has been satisfied. BG Grp. PLC v. Republic of Arg., 134 S. Ct. 1198 (2014) (No. 12-138). Here, a treaty between the United Kingdom and Argentina required aggrieved investors to pursue claims against either of the two countries in the host country’s courts for at least 18 months before resorting to arbitration. An investor invoked the arbitration clause without first filing a claim in an Argentine court. The district court denied Argentina’s motion to vacate the arbitral award, rejecting the argument that an arbitration precondition had not been satisfied. The appellate court reversed. It found that the court was empowered to determine that the arbitrator was wrong to exercise jurisdiction over the dispute. The Supreme Court agreed with the district court, and found that the precondition was a matter for the arbitrator to interpret and apply, and the courts should review the arbitrator’s interpretation with deference.