Despite the numerous Supreme Court decisions limiting class arbitrations, one central issue remains undecided: who decides whether an arbitration agreement permits class arbitration, the courts or the arbitrators? Entities that want to avoid class arbitration want the question to be decided by the courts, where the appeal process ensures at least one level of review. Leaving the issue in the hands of an arbitrator only opens up the possibility, however remote, that the arbitrator will construe an agreement to permit class arbitration and that the decision may not be effectively reviewable.