The case involves a breach of contract lawsuit by a company against a union for continuing a strike despite a no-strike-clause in a new collective bargaining agreement. At issue was the ratification date of the agreement, which the Ninth Circuit held should be decided by an arbitrator. The Ninth Circuit had reasoned that the contract clause requiring arbitration covered the ratification-date dispute because it was a strike-related claim; that national policy favoring arbitration required a resolution in favor of arbitration; and that the company had implicitly consented to arbitrate the ratification-date dispute by suing under the contract.

The Supreme Court disagrees with this reasoning. “Whether parties have agreed to arbitrate a particular dispute is typically an ‘issue for judicial determination,’” the Court says. In cases invoking the “federal policy favoring arbitration of labor disputes,” the courts must “discharge their duty to satisfy themselves that the parties agreed to arbitrate a particular dispute by (1) applying the presumption of arbitrability only where a validly formed and enforceable arbitration agreement is ambiguous about whether it covers the dispute at hand and (2) ordering arbitration only where the presumption is not rebutted,” the Court rules. Granite Rock Co. v. Teamsters