A judge said brokers can earn interest on deposits.

Refco Inc. said a federal district judge ruled that the Chicago-based firm and three other futures commission brokers--Merrill Lynch Futures, Clayton Brokers and Futures Discount Group--were within their rights under federal law in retaining interest earned by investing their customers’ margin deposits. U.S. District Judge James Moran in Chicago made the ruling in a case brought by William A. Craig of California.