American Airlines has asked a judge to stop a federal agency from overseeing a union-organizing election for customers-service agents.
The National Mediation Board scheduled the election to run June 21 through Aug. 2.
American on Monday asked a federal judge in Fort Worth for an injunction.
The airline says a federal law signed in February means the Communications Workers of America needs signatures from 50 percent of eligible workers before any election. The union says it met a lower, 35-percent requirement in effect when it filed last year.
American in May sued the mediation board, but last week the panel ordered the election to proceed.
American is a unit of Fort Worth-based AMR Corp., which last fall sought bankruptcy protection.