A union of immigration judges is suing the Department of Justice over a policy allegedly restricting them from speaking publicly about immigration and other issues in violation of their constitutional rights, the latest escalation of tensions between the union and the federal department where they work.

The lawsuit, filed Wednesday on behalf of the National Association of Immigration Judges by attorneys with the Knight First Amendment Institute and Virginia attorney Victor Glasberg, says DOJ’s Executive Office for Immigration Review in 2017 began requiring the judges to seek preapproval to speak in their own capacity, and not on behalf of the office.