Will the U.S. Supreme Court re-interpret the Federal Arbitration Act to give corporations a license to steal? That is the issue in American Express Co. v. Italian Colors Restaurant, argued on Feb. 27.

Filed by a group of small merchants, the class action claims that American Express violated the antitrust laws by using its monopoly power in the corporate and premium charge-card market to require them to accept mass-marketed AmEx credit cards, too — and then overcharging them by 30 percent.