Boston Fights Trump’s Legal Attack on Sanctuary City Policy (1)

A Trump administration attempt to strike down Boston’s sanctuary city law can’t overcome constitutional hurdles protecting localities from federal incursions, the city said in filings asking a judge to toss the government’s lawsuit.

“Here, Boston has declined” the invitation to assist the federal government’s immigration crackdown, “and the Tenth Amendment protects the City’s authority to do so,” Boston said in its Monday filing.

The Justice Department had said Boston’s Trust Act raised its own constitutional issues, arguing in the complaint that the non-cooperation amounted to illegal obstruction of immigration efforts by strictly limiting the city’s cooperation with federal authorities. The lawsuit is part of the administration’s broad immigration enforcement efforts and push to accelerate the rate of deportations from the US.

The bid to spike the Department of Justice’s sanctuary city lawsuit urged the court to find the local ordinance is protected by the Tenth Amendment, which says all powers not explicitly granted to the federal government are reserved to the states. A federal judge invoked that protection in July when dismissing a similar action filed against Illinois, the city of Chicago and Cook County.

The DOJ has also targeted New York City, Los Angeles, and Rochester, NY with sanctuary city lawsuits.

Boston said the Trump administration is wrong in arguing that the federal Immigration and Nationality Act mandates local participation in enforcement efforts. The city’s ordinance, known as the Boston Trust Act, also doesn’t stand as an obstacle to federal authorities conducting enforcement actions.

Trust Act

Boston enacted the Trust Act in 2014, limiting what information city police will share and denying federal officers access to suspects in city custody who are thought to be in the country illegally. The measure was designed to promote trust between local police and immigrant communities.

The ordinance preceded the Massachusetts Supreme Judicial Court’s 2017 Lunn v. Commonwealth ruling that found municipalities have no authority to honor civil detainer requests that immigration officials issue asking localities to detain people until they can be taken into custody by federal authorities.

The Trust Act says local police also can’t ask people their immigration status, give detainees’ release dates to Immigration and Customs Enforcement, make arrests based on ICE administrative warrants or perform functions of an immigration officer.

The law does allow police to provide criminal history information to the Department of Homeland Security Investigations division of ICE and collaborate on investigations related to human trafficking, child exploitation, drug and weapons trafficking, and cybercrimes.

In 2024, Boston police denied 15 civil immigration detainer requests and neither detained nor transferred any individuals to ICE custody, according to city records.

No Obligation

Boston told the court that the Immigration and Nationality Act doesn’t oblige states or localities to help the government in its immigration duties, and courts have ruled that invitations to assist in those federal duties can be declined without amounting to obstruction.

The federal law doesn’t create a mandate for information sharing or honoring civil detainer requests, according to the motion. The city’s decision to not engage in either “reflects its choice of how to deploy limited resources and is not an obstacle to the enforcement of federal law.”

The city also rejected the Trump administration’s claim that the ordinance amounts to illegal regulation of the federal government.

In an emailed statement, Boston Mayor Michelle Wu said the city will not “participate in mass deportation.”

“Boston will continue to work with state and federal law enforcement to protect our residents,” Wu added, “but we are challenging this meritless and unconstitutional attack on our local authority.”

Representatives for the DOJ weren’t immediately available for comment.

The city is represented by in-house attorneys and the Public Rights Project.

The case is U.S. v. City of Boston, D. Mass., No. 1:25-cv-12456, filed on 11/17/25.