Metro filed suit against its union in a growing dispute about new criminal background checks of rail and bus workers, which take effect next month.

The union has been challenging Metro’s system of performing criminal background checks of rail and bus employees.

The agency and union are scheduled to attend a June 19 arbitration hearing on the issue. But court filings reviewed by the News4 I-Team show Metro is asking a federal judge to intervene and stop the arbitration hearing, arguing the agency has sole discretion over hiring and firing.

Metro’s transit union said the agency is expanding its background check system to include random screenings of workers. The union said the change will take effect July 1 and will result in the removal of “quite a few” rail and bus employees.

Amalgamated Transit Union Local 689 President Jackie Jeter said Metro should instead attempt to collectively bargain changes to its hiring and firing practices. Notice of the changes were not given to all bus and rail employees to sign or acknowledge, Jeter said.

Jeter said Metro made efforts in the 1990s and 2000s to hire people with criminal records. She said a large number of those people could be impacted by Metro’s new criminal background check system.

In its newly filed civil suit against the union, Metro argues a judge should prevent the union from challenging the criminal background screenings, including the June 19 arbitration hearing. In its court filings, Metro said, “Local 689 agreed that WMATA expressly reserves all matters pertaining to the management of operations, including the hiring and establishment of standards for selection and qualification of employees.”

A Metro spokesman told News4, “We do not comment on active or pending litigation.”

The agency and its union have had prior disputes over the criminal background check process. Some of those disputes have triggered protests.