The arbitration clause in Rafael Crespo’s employment contract was just that-a clause, short and sweet. And that was its undoing.

Mr. Crespo was a building supervisor on New York’s West Side until the building owners fired him in 1995. He wanted to sue them, but his bosses insisted that he was barred by a clause his union had negotiated saying that “all differences” over the “application or performance of any part” of the contract must go to binding arbitration. His attorneys responded that the simple reference to “all differences” didn’t cover his complaint that he was fired in violation of the law against age discrimination.