In Oxford Health Plans v. Sutter, the Supreme Court today upheld an arbitrator's decision that a particular arbitration clause authorized class arbitration. Justice Kagan wrote the main opinion, which was unanimous. The standard of review of arbitrators' decisions under the Federal Arbitration Act is highly deferential. So "the sole question for us," Justice Kagan explained, "is whether the arbitrator (even arguably) interpreted the parties’ contract, not whether he got its meaning right or wrong." The Court agreed that the arbitrator was interpreting the contract, and that was that. There's a concurring opinion written by Justice Alito in which Justice Thomas joined, suggesting that any eventual class arbitration judgment in the case would be susceptible to collateral attack.