This case presents a familiar pattern for the Court. The court of appeals’ ruling is indefensible. So the respondent has advanced an alternative ground for deciding the case in its favor that is not encompassed by the Question Presented and was not pressed in or passed upon by the court of appeals. Even if this Court were to decide that argument, it lacks merit.

The D.C. Circuit obviously erred in holding that courts rather than arbitrators presumptively determine compliance with preconditions to arbitration. See Part I.A, infra. Argentina has waived its newfound argument that the eighteenmonth litigation provision (Local Litigation Provision) of the U.K.-Argentina bilateral investment treaty (Treaty)1 is a condition on the existence of the parties’ arbitration agreement, not a precondition to commencement of arbitration. See Part I.B, infra.

Argentina’s new argument also fails for two independent reasons: it is wrong and it is irrelevant. The Local Litigation Provision is indistinguishable from the measures that this Court has determined are procedural preconditions to arbitration. See Part II.A, infra. In any event, no matter how the provision is characterized, the parties intended that the expert arbitral tribunal, not a U.S. court, would determine its application. See Part II.B, infra.