In AT&T Mobility v. Concepcion, the U.S. Supreme Court told us that the Federal Arbitration Act overrides state contract law if a contract contains an arbitration clause. In American Express v. Italian Colors Restaurant, the Court upheld an arbitration agreement's class action waiver even when the cost of arbitrating a federal antitrust claim would exceed the recovery amount.
This approach has it critics. Notably, Judge Richard Posner said that class action waivers effectively eliminate litigation: "The realistic alternative to a class action is not 17 million individual suits, but zero individual suits, as only a lunatic or a fanatic sues for $30."
Looking into my crystal ball, I foresee Alltel Communication v. Rosenow to be the Supreme Court's next class action/arbitration case.