Federal Government Sues Boston, Escalating Clash Over Sanctuary Cities

Michelle Wu delivering her 2025 State of the City address. Courtesy of Wikimedia Commons.

On September 4, 2025, the Department of Justice (DOJ) filed a lawsuit in federal court against the City of Boston, Mayor Michelle Wu, and the Boston Police Department. The suit alleges that the city’s sanctuary laws, which limit local police cooperation with Immigration and Customs Enforcement (ICE) detainer requests, are illegal and “interfere with the federal government’s enforcement of its immigration laws.” 

These requests, specifically immigration detainers, are formal requests from ICE to a law enforcement agency to hold an individual in custody for up to 48 hours after the time they would have been released.

The lawsuit was followed days later by “Operation Patriot 2.0,” a series of ICE arrests in Massachusetts that Homeland Security officials explicitly linked to Wu’s policies. The operation was framed by DHS officials as a direct response to city policy, with DHS Assistant Secretary Tricia McLaughlin asserting in a September 9 press release that “Sanctuary policies like those pushed by Mayor Wu not only attract and harbor criminals but protect them at the peril of law-abiding American citizens.” The release detailed the arrests of seven individuals, listing charges that included aggravated rape, child abuse, and drug trafficking.

The legal battle hinges on the Boston Trust Act, a city ordinance originally passed unanimously in 2014 and reaffirmed by the city council in 2024. The law was championed by Mayor Marty Walsh and Councilor Josh Zakim, its core rationale being to ensure that immigrants, regardless of status, would feel safe reporting crimes and cooperating with police, thereby enhancing public safety for everyone.

The law limits local police cooperation with federal immigration authorities, and prohibits detainment of individuals based only on an ICE detainer request; a criminal warrant from a judge is required. The act is a classic ‘sanctuary’ policy, defined by the Justice Department as those that “refuse to honor ICE detainer requests unless there is a warrant signed by a judge.”

Since the Justice Department labeled Boston a “sanctuary jurisdiction” in early August 2025, the city has become a battleground for the Trump administration’s campaign against local immigration policies. The conflict escalated rapidly in September this year, with a federal lawsuit against Mayor Wu and an intensive ICE operation, consequently transforming the city’s mayoral race into a referendum on resistance to federal immigration enforcement. 

In her response to the Justice Department, Wu challenged this narrative by emphasizing the city’s solid efforts to tackle crime, often in partnership with federal authorities. She pointed to the Boston Police Department's collaborative work on counterterrorism, port security, and combating drug trafficking as evidence that the city is committed to public safety, undermining the administration's characterization.

Wu framed the lawsuit and ICE operations as “false and continuous attacks on American cities,” accusing the administration of targeting Boston for its “refusal to bow down to unconstitutional threats and unlawful coercion.” This positioning of the city’s resistance as a defense of its values counters the federal government’s accusations of Boston obstructing justice.

While visiting polls during Boston’s preliminary election on September 9, 2025, Wu said that the Trump administration is targeting Boston because it “represents all that is good about our democracy.” According to Wu, Boston “need[s] a leader who is accessible, who’s accountable, who’s connected.” 

This stance resonated powerfully with the city, with polling that showed 67% of Boston voters approved of her refusal to drop the city's sanctuary policies. Her main opponent, Josh Kraft, was also critical of the Trump administration's attacks, which meant Wu's defense of the policy did not become a major point of contention in the race.

For Mayor Wu, the federal government’s actions may have become an asset to her election support. She advanced in the election with 72% of the vote, while Kraft dropped out of the race two days after the primary. 

Jeffrey Berry, a Boston political analyst and professor emeritus at Tufts University, said Wu has become a “symbol of democratic resistance to the president,” a powerful position in a city like Boston, where voters overwhelmingly disapprove of the administration's actions such as sending the National Guard. 

David Woodruff, a Boston voter and retired MIT research support specialist, says he voted for Wu because of “the way she stands up to Trump,” and “what she’s been doing on the national scene.” In a deeply Democratic city, a leader who effectively embodies resistance to a Republican administration is able to consolidate support across the electorate, turning a federal challenge into a local political asset.

Meanwhile, rhetoric from federal officials paints a different picture of the city. The ICE press release argued that “criminal illegal aliens flock to Sanctuary cities like Boston, where politicians will allow them to terrorize innocent Americans.” By using language like “flock,” which suggests a deliberate and overwhelming influx, and “terrorize,” which frames the issue as one of intentional violence and fear, the administration portrays Boston as a place where the government is complicit in the endangerment of its own residents. This is a stark contrast to the city's own framing of its policies as promoting safety and community trust.

The lawsuit against Boston is far from an isolated case; it represents the latest in a series of legal challenges brought by Attorney General Pam Bondi's DOJ against major metropolitan areas. On August 5, 2025, the Justice Department published a list of states, cities, and counties it accused of having policies that “impede enforcement of federal immigration laws”. 

The list includes twelve states, as well as  major cities such as  Chicago, Los Angeles, Philadelphia, and Seattle. The administration's criteria for this list include limiting information sharing with ICE, refusing to honor ICE detainer requests without a judicial warrant, and restricting ICE access to local jails. The lawsuit against Boston, filed just weeks after this list was published, represents the administration following through on the vow to challenge these policies in court.

The simultaneous federal and local political pressure on Boston suggests a strategy of using immigration enforcement as a means  to undermine local autonomy. The case, at its core, is a constitutional conflict with two clashing principles: the DOJ will argue that immigration is exclusively a federal matter, and local authorities are an interference. Boston’s lawyers are likely to assert that the federal government cannot command local enforcement and resources. 

Even with Wu running unopposed for a second term, the outcome of the DOJ lawsuit will likely have significant implications that extend far beyond Boston. Ultimately, the ruling will determine the balance between federal authority and local autonomy, setting a decisive precedent for the future of sanctuary cities across the United States.