Opinion of the Court
stay litigation “upon being satisfied that the issue” is “referable to arbitration” under the “agreement.” Section 4 says that a court, in response to a motion by an aggrieved party, must compel arbitration “in accordance with the terms of the agreement” when the court is “satisfied that the making of the agreement for arbitration or the failure to comply therewith is not in issue.”
Archer and White interprets those provisions to mean, in essence, that a court must always resolve questions of arbitrability and that an arbitrator never may do so. But that ship has sailed. This Court has consistently held that parties may delegate threshold arbitrability questions to the arbitrator, so long as the parties’ agreement does so by “clear and unmistakable” evidence. First Options, 514 U. S., at 944 (alterations omitted); see also Rent-A-Center, 561 U. S., at 69, n. 1. To be sure, before referring a dispute to an arbitrator, the court determines whether a valid arbitration agreement exists. See 9 U. S. C. §2. But if a valid agreement exists, and if the agreement delegates the arbitrability issue to an arbitrator, a court may not decide the arbitrability issue.
Second, Archer and White cites §10 of the Act, which provides for back-end judicial review of an arbitrator’s decision if an arbitrator has “exceeded” his or her “powers.” §10(a)(4). According to Archer and White, if a court at the back end can say that the underlying issue was not arbitrable, the court at the front end should also be able to say that the underlying issue is not arbitrable. The dispositive answer to Archer and White’s §10 argument is that Congress designed the Act in a specific way, and it is not our proper role to redesign the statute. Archer and White’s §10 argument would mean, moreover, that courts presumably also should decide frivolous merits questions that have been delegated to an arbitrator. Yet we have already rejected that argument: When the parties’ contract assigns a matter to arbitration, a court may not
