Kagan, J., dissenting
term) enables an adjudicator to determine a contract’s meaning. To the contrary, the Court disclaimed any view on that question. Yes, the Court held, “a contractual basis” was needed for class arbitration. Ibid. (emphasis added). But given the panel’s reliance on policy alone, the Court explained that it had “no occasion to decide what contractual basis” was required. Id., at 687, n. 10 (emphasis added); see Oxford Health Plans LLC v. Sutter, 569 U. S. 564, 571 (2013) (“We overturned the arbitral decision [in Stolt-Nielsen] because it lacked any contractual basis for ordering class procedures,” not because it relied on an inadequate one).
Indeed, parts of Stolt-Nielsen—as well as later decisions—indicate that applying the anti-drafter rule to ambiguous language provides a sufficient contractual basis for class arbitration. In Stolt-Nielsen, we faulted the arbitrators for failing to inquire whether the relevant law “contain[ed] a default rule” that would construe an arbitration clause “as allowing class arbitration in the absence of express consent.” 559 U. S., at 673 (internal quotation marks omitted). We thus implied that such a default rule—like the anti-drafter canon here—can operate to authorize class arbitration when an agreement’s language is ambiguous. And that is just how Concepcion (the other decision the majority relies on, see ante, at 7–8, 10–12) understood Stolt-Nielsen’s reasoning. Said Concepcion: We held in Stolt-Nielsen “that an arbitration panel exceeded its power [by] imposing class procedures based on policy judgments rather than the arbitration agreement itself or some background principle of contract law that would affect its interpretation.” 563 U. S., at 347 (emphasis added); see Oxford Health, 569 U. S., at 571 (similarly noting that Stolt-Nielsen criticized the arbitrators for failing to consider whether a “default rule” resolved the class arbitration question (internal quotation marks omitted)). The Court has thus (rightly) viewed the use of
