United States v. City of Boston: Defending the Boston Trust Act
By Sam Dinning, Patrick Archer, and Toby Merrill
Among this federal administration’s many targets, cities have been a constant focal point. The federal government has taken aim at countless local actions, from housing policy to election administration. Most notably, it has used every available lever to try to coerce cities into abandoning so-called “sanctuary” policies.
Recently, the City of Boston denied the administration one such attempt, winning dismissal of the administration’s lawsuit that aimed to compel Boston’s cooperation with federal immigration enforcement in United States v. City of Boston, No. 25-cv-12456 (D. Mass.). The lawsuit and its resolution echo a growing pattern across the country: federal courts have uniformly rejected the administration’s blatantly unconstitutional attempts to co-opt state and local policymaking.
The federal government’s case against Boston centered on the Boston Trust Act, Bos., Mass., Mun. Code ch. 11, § 1.9 (“Trust Act”), which was first enacted in 2014. The Trust Act prohibits local law enforcement from detaining individuals solely based on civil immigration detainer requests. It also restricts local officials from sharing individuals’ personal information with federal civil immigration officials. Id. § 1.9(D)(3).
As a legal matter, deciding local policies like the Trust Act is Boston’s prerogative. And as a practical matter, the Trust Act works by ensuring that all Boston residents can rely on the Boston Police Department to ask for help or report a crime and making clear that Boston policing resources will always focus on criminal law enforcement.
The administration sued Boston in September 2025, advancing a broad and unsupported view of the Supremacy Clause (U.S. Const. art. VI, cl. 2). The complaint essentially argued that because the federal government has broad authority over immigration enforcement, it could compel cities and states to carry out policies that further federal immigration goals. Specifically, the administration claimed that the Trust Act was preempted by federal immigration laws and violated the intergovernmental immunity doctrine by regulating and discriminating against the federal government. Boston moved to dismiss the complaint, explaining that federal law makes local cooperation with immigration enforcement voluntary and that the Trust Act regulates only Boston officials, as is the Boston’s prerogative. Above all, the City of Boston’s policymaking and resource deployment are protected by the Tenth Amendment (U.S. Const. amend. X); the federal government cannot commandeer local resources to further its own priorities.
Ultimately, the court found that the administration’s case failed before even reaching the merits. The court focused on standing, holding that it could not redress the federal government’s alleged injuries. Although ill-defined in the complaint, the federal government’s asserted injuries included “increased operational costs to enforce federal immigration law” and a “sovereign harm” stemming from the existence of the allegedly illegal city ordinance. See United States v. City of Boston, No. 25-cv-12456, ECF No. 72 at 17-20 (May 28, 2026) (Order Granting Motion to Dismiss). But the court properly recognized that even if Boston wanted to comply with federal detainer requests—which it does not and has not for more than a decade—state law would not allow it to, so even a favorable outcome in this case would provide the federal government no redress. See id. (citing Lunn v. Commonwealth, 78 N.E.3d 1143 (Mass. 2017)).
The federal government has filed a notice of appeal, so these issues will soon be before the First Circuit.
Boston’s resounding win is just the latest in the administration’s cases against so-called “sanctuary” policies. To date, the federal government has filed at least a dozen such cases, from Los Angeles to Chicago to New Haven. These lawsuits have uniformly failed. More than a dozen courts have ruled in favor of states and localities, dating back to the last Trump Administration. See United States v. City of Newark, No. 24-cv-5081 (D.N.J.); United States v. City of Los Angeles, No. 25-cv-5917 (C.D. Cal.); United States v. Colorado, No. 25-cv-1391 (D. Colo.); United States v. New York, No. 25-cv-205 (N.D.N.Y.); United States v. New York, No. 25-cv-744 (N.D.N.Y.); United States v. Illinois, No. 25-cv-1285 (N.D. Ill.); United States v. New Jersey, No. 20-cv-1364 (D.N.J.); McHenry Cnty. v. Raoul, 574 F. Supp. 3d 571 (2021), aff’d, 44 F.4th 581 (7th Cir. 2022); Ocean Cnty. Bd. of Comm’rs v. Att’y Gen. of N.J., 8 F.4th 176 (3d Cir. 2021); United States v. California, , 921 F.3d 865 (9th Cir. 2019). None has ruled in favor of the federal government. These decisions have primarily been on the merits, with courts emphasizing the voluntariness of local participation in immigration enforcement under federal law, the Tenth Amendment implications of the compulsory local participation the federal government seeks, and the United States’ overbroad and unsupported reading of federal information-sharing requirements.
Moreover, courts across the country have chided the federal government for continuing to recycle previously rejected preemption and intergovernmental immunity arguments, often without acknowledging that these interpretations of the law, including 8 U.S.C. § 1373, have been rejected “without exception” in other cases to consider them. See, e.g., United States v. New York, 814 F. Supp. 3d 266, 277 (N.D.N.Y. 2025) (“find[ing] it unnecessary to spill further judicial ink on the issue”); United States v. City of Boston at 16 n.10 (“The United States’ briefing in this case largely ignored these thoughtful, persuasive opinions [in similar cases] and did not attempt to explain why this Court should reach a different conclusion on the merits .…”).
Despite this overwhelming negative precedent, the federal government seems undeterred, continuing to bring nearly identical claims across the country. In fact, Public Rights Project—whose attorneys served as co-counsel on this case—recently filed motions to dismiss two other suits challenging similar policies in Albuquerque, New Mexico, and New Haven, Connecticut.
This unabashedly political pursuit is disappointing, if not surprising. But it reflects an important fact: cities and states are where government most touches people’s lives every day. The federal government wants to control local policy because local policy matters. And to date, courts have widely prevented the federal government from infringing on the state and local authority protected by the Tenth Amendment. In Minnesota recently, a federal court went so far as to find that certain federal subpoenas were “an unconstitutional effort to coerce Minnesota officials” into complying with federal immigration policy preferences. In re Grand Jury Subpoenas, No. 26-mc-43 (D. Minn. June 22, 2026). Courts are seeing these federal actions for what they are, and the consistent decisions reinforcing the boundaries of federal authority—at least with respect to cities and states—are a heartening reminder of the virtues of our federal system: preventing co-optation of local resources, ensuring political accountability, and mitigating the threat of tyranny.
Patrick Archer is a Legal Fellow at Public Rights Project. He assists cities and counties in defending the civil rights of their community members in a number of ways, including by protecting so-called “sanctuary” policies from federal government challenges. He appears on behalf of Boston in United States v. City of Boston.
Sam Dinning is the Chief of Staff & Policy for the City of Boston Law Department. Sam works on a variety of matters at the intersection of law and policy and has led the City’s legal response to federal policy actions. He appears on behalf of Boston in United States v. City of Boston.
Toby Merrill is the Litigation Director at Public Rights Project. She represents local governments across the country to defend and enforce civil rights. She appears on behalf of Boston in United States v. City of Boston.
