For the past few years, courts throughout the U.S. have repeatedly struck down class action waivers under state unconscionability law. In a sweeping decision, the U.S. Supreme Court reversed that trend, handing down its much-awaited decision in AT&T Mobility v. Concepcion, 131 S. Ct. 1740 (U.S. 2011). The arbitration provision at issue was part of an AT&T service contract, requiring the Concepcions to arbitrate any disputes with AT&T and prohibiting them from adjudicating their disputes as part of a class action. In a 5-4 decision, the Supreme Court held that AT&T’s arbitration clause was enforceable despite the class action waiver. The issue decided by the Court was whether the Federal Arbitration Act, 9 U.S.C. § 1 et seq. (FAA) preempts California’s common law of unconscionability, pursuant to which California courts have struck most class action waiver clauses since 2005. The Supreme Court held that AT&T’s arbitration agreement was enforceable notwithstanding the class action waiver because California law conflicts with—that is, is preempted by— the FAA. This decision will affect the class action exposure of businesses in a wide span of industries, and once again places class action waivers on equal footing with other contractual provisions that companies include in their arbitration agreements.