The Trump administration is suing Boston over sanctuary city policies that shield illegal immigrants from federal enforcement.

The U.S. Department of Justice filed a lawsuit in a Massachusetts U.S. District Court last Thursday against Boston Mayor Michelle Wu, Boston Police Commissioner Michael Cox, and the City of Boston. Prosecutors argue the city’s policies violate federal law and endanger residents.

“The City of Boston and its Mayor have been among the worst sanctuary offenders in America – they explicitly enforce policies designed to undermine law enforcement and protect illegal aliens from justice,” U.S. Attorney General Pam Bondi said in a press release.

“If Boston won’t protect its citizens from illegal alien crime, this Department of Justice will,” Bondi added.

The lawsuit targets the Boston Trust Act, which prevents police from honoring Immigration and Customs Enforcement detainers unless a criminal warrant is issued. ICE uses detainers to take custody of foreign nationals with criminal charges or convictions.

Passed in 2014, the Boston Trust Act made Boston a sanctuary city. The state's other seven sanctuary cities include: Amherst, Boston, Cambridge, Chelsea, Concord, Newton, Northampton, and Somerville.

The federal Justice Department said Boston ICE has issued detainers for suspects facing “violent and serious” charges, including homicide, sex crimes, and drug-related offenses, according to the release. Officials argue these criminals should never be allowed back on the streets once they are in custody, but that Wu’s policy ensures many walk free.

“Not only are Boston’s sanctuary city policies illegal under federal law, but, as alleged in the complaint, Boston’s refusal to cooperate with federal immigration authorities results in the release of dangerous criminals from police custody who would otherwise be subject to removal,” the Justice Department said in its press release.

Wu responded to the lawsuit by calling it "unconstitutional."

“This unconstitutional attack on our city is not a surprise,” Wu said in a written statement. “Boston is a thriving community, the economic and cultural hub of New England, and the safest major city in the country — but this administration is intent on attacking our community to advance their own authoritarian agenda.”

“This is our City, and we will vigorously defend our laws and the constitutional rights of cities,” she said. “We will not yield.”

The Massachusetts Fiscal Alliance applauded the lawsuit and said Wu is putting politics above safety.

“Mayor Wu has made it her mission to put ideology above public safety, the law, and efficient government," MassFiscal executive director Paul D. Craney said in a press release. "Boston’s so-called ‘Trust Act’ isn’t about trust at all. It’s about shielding people here illegally from lawful federal enforcement and tying the hands of local police officers. Now, taxpayers are left paying the price for a policy that makes their city less safe, and the Department of Justice is stepping in to do what Wu refuses to: protect the people of Boston."

Craney concluded: “Boston’s sanctuary policies are reckless, costly, and dangerous. Mayor Wu must be held accountable, and Governor Healey must act to end them before more people are put at risk.”

A press spokesman for Boston Mayor Michelle Wu could not be reached for comment this past weekend.