WASHINGTON — Metro’s largest union dropped its appeal Monday of a federal court’s decision ordering new elections.

The July decision found “clear violations” by Amalgamated Transit Union Local 689 of federal rules governing 2015 union elections that included delayed notice and irregularities in who was allowed to run.

The union had filed a notice of appeal in August while the local and Metro remained in heated contract talks, and lawyers were due to file the first briefs in the appeal by Monday evening.

Instead, the union filed a notice Monday to the Fourth Circuit Court of Appeals in Richmond that it is dropping the case.

That means new elections will be required. Without a court order, the union’s next elections had been planned for November 2018.

In early September, the union gave up on negotiations with Metro over a new contract after more than a year of working without a new agreement. The contract details will now be decided by a three-member arbitration panel.