Maine has asked a judge to dismiss a lawsuit filed by the U.S. Department of Justice that alleges the state is illegally denying federal immigration officers access to confidential license plates.

The DOJ sued Maine in U.S. District Court in late May. The lawsuit alleges that by denying federal officers access to confidential plates for federal civil immigration enforcement, the state is discriminating against the government and attempting to regulate its operations.

The state’s program for confidential plates, which is overseen by the Bureau of Motor Vehicles and the secretary of state, was briefly paused for a policy review in January, the state said in court records. By May, the office had resumed taking applications with a new rule: Confidential plates could not be used for federal immigration enforcement, unless it was part of an authorized criminal investigation.

In a motion to dismiss the lawsuit filed Monday, attorneys for the state called it a “constitutionally protected policy choice” to not offer “Maine resources, property or regulatory framework” to assist with federal immigration enforcement. According to the motion, the same rules apply to all officers seeking confidential plates, regardless of whether they work for the state or federal government.

“If there is legitimate immigration policy to pursue within State borders, Maine is not stopping the federal government from executing it,” Halliday Moncure and Paul Suitter, assistant attorneys general, wrote. “It has not attempted to bar federal vehicles from its roads. Nor does Maine subject the federal government to any special requirement before entering the State.”

Maine has allowed officers to obtain confidential plates for more than 10 years, according to the state’s filings.

According to the state’s motion, the DOJ complained to Attorney General Aaron Frey — who is also named in the lawsuit — about two weeks before the lawsuit was filed.

“If federal law enforcement vehicles are readily identifiable, either by a government plate or through a state plate and registration that is subject to public exposure through an information request, then officers, their families, and people under their protection will all be at risk,” Assistant Attorney General Brett Shumate from the DOJ’s civil division wrote in a May 12 letter.

Frey told the DOJ that there wasn’t anything discriminatory in Maine’s policy, according to a copy of his response that was included in court records. He told Shumate that Maine had approved 48 requests for confidential plates for federal officers, from eight federal agencies, between January and May 2026. He also reported that about two dozen requests from Department of Homeland Security officers were denied because their applications appeared to contain “material false statements” that contradicted applications submitted by U.S. Immigration and Customs Enforcement, according to the motion.

DOJ attorneys and a spokesperson for the department did not immediately respond to a request for comment Tuesday.

Several advocacy groups who have been involved this year in challenging the constitutionality of federal agents detaining immigrants in Maine also filed motions supporting the state.

The parties include the American Civil Liberties Union of Maine, the Immigrant Legal Advocacy Project, Pine Tree Legal Assistance and the Refugee and Human Rights Clinic at the University of Maine School of Law. In a court filing, the groups said they have observed an increase in what they described as unconstitutional acts by immigration officers, including the fatal shooting of Johan Sebastián Durán Guerrero in Biddeford on July 13. They argued that Maine had a right to regulate its state-run program for confidential plates.

“Forcing Maine to issue confidential plates under the state name, with the distinctive Pine Tree design, and under a state program to make the license plate untraceable, would blur responsibility for the actions taken by immigration enforcement officers in Maine,” the groups argued.