The complaint says the city acted unconstitutionally by regulating federal law enforcement. U.S. Attorney Scott Bradford, who represents the District of Oregon, said the policy could hinder federal officers’ work and put them at risk.

Portland’s City Council approved the policy in May by an 8-4 vote. Councilor Sameer Kanal introduced it, citing concerns about people impersonating federal immigration officers. Kanal said Thursday that he could not discuss the lawsuit, but argued that identifiable officers promote transparency and strengthen trust between agencies and communities.

The policy drew opposition from Mayor Keith Wilson and the city’s police union, which warned it could violate labor laws and lead to litigation. Councilor Steve Novick, who voted for the measure, said in May that he saw a high likelihood it would be struck down, but believed the city had strong legal arguments and that the issue was worth pursuing.

The lawsuit follows a federal appeals court ruling Wednesday that struck down a California law requiring U.S. Immigration and Customs Enforcement officers to display visible identification. The court said the law conflicted with the Constitution’s Supremacy Clause, which establishes that federal law takes precedence over state law.

The Justice Department’s complaint against Portland does not address a separate Oregon law that also bans law enforcement officers from wearing face coverings. The federal government filed a similar suit against St. Paul, Minnesota, on Thursday and has brought comparable cases against jurisdictions including New York, Virginia, Connecticut, New Jersey, Maryland, Philadelphia, Denver and Milwaukee.