The U.S. Court of Appeals for the Second Circuit insisted yesterday that a mandatory arbitration clause in American Express’ contracts with merchants that includes a class action waiver is unenforceable as against public policy.

The circuit was told last year by the U.S. Supreme Court to take a second look at its 2009 decision in In re: American Express Merchants’ Litigation, 06-1871, finding the arbitration clause unenforceable under the Federal Arbitration Act (FAA).