Opinion of the Court
For example, we presume that parties have not authorized arbitrators to resolve certain “gateway” questions, such as “whether the parties have a valid arbitration agreement at all or whether a concededly binding arbitration clause applies to a certain type of controversy.” Green Tree Financial Corp. v. Bazzle, 539 U. S. 444, 452 (2003) (plurality opinion). Although parties are free to authorize arbitrators to resolve such questions, we will not conclude that they have done so based on “silence or ambiguity” in their agreement, because “doing so might too often force unwilling parties to arbitrate a matter they reasonably would have thought a judge, not an arbitrator, would decide.” First Options, 514 U. S., at 945 (emphasis added); see also Howsam, 537 U. S., at 83–84. We relied on that same reasoning in Stolt-Nielsen, 559 U. S., at 686–687, and it applies with equal force here. Neither silence nor ambiguity provides a sufficient basis for concluding that parties to an arbitration agreement agreed to undermine the central benefits of arbitration itself.[1]
B
The Ninth Circuit reached a contrary conclusion based on California’s rule that ambiguity in a contract should be construed against the drafter, a doctrine known as contra proferentem. The rule applies “only as a last resort” when the meaning of a provision remains ambiguous after exhausting the ordinary methods of interpretation. 3 A. Corbin, Contracts §559, pp. 268–270 (1960). At that point, contra proferentem resolves the ambiguity against the drafter based on public policy factors, primarily equitable
- ↑ This Court has not decided whether the availability of class arbitration is a so-called “question of arbitrability,” which includes these gateway matters. Oxford Health Plans LLC v. Sutter, 569 U. S. 564, 569, n. 2 (2013). We have no occasion to address that question here because the parties agreed that a court, not an arbitrator, should resolve the question about class arbitration.
