8 USC 1373 is a short federal statute that bars state and local governments from restricting the flow of citizenship or immigration status information to federal immigration authorities. It does not require any government to collect that information, ask about it, or act on it. That distinction is the reason most sanctuary policies survive legal challenge, and it is the reason fights over the statute keep landing in court.
What the Statute Prohibits
The law has two operative parts. Subsection (a) says no federal, state, or local government entity or official may prohibit or restrict any government entity or official from sending or receiving information about a person’s citizenship or immigration status to or from federal immigration authorities. Subsection (b) says no person or agency may restrict a government entity from requesting, receiving, maintaining, or exchanging that information with federal immigration authorities or other government entities.1Office of the Law Revision Counsel. 8 USC 1373 – Communication Between Government Agencies and the Immigration and Naturalization Service
The statute still names the “Immigration and Naturalization Service,” an agency abolished in 2003. Its functions moved to the Department of Homeland Security, and references to INS in federal law now apply to DHS and its sub-agencies, including Immigration and Customs Enforcement.
What the Statute Does Not Require
Section 1373 prohibits restrictions on communication. It does not command anyone to communicate. A city can tell its police officers never to ask about immigration status during routine encounters, and that policy does not violate the statute, because officers who never collect the information have nothing to share and nothing to restrict.
That gap between collection and communication is where sanctuary policies live. A jurisdiction that says “our officers will not ask about immigration status” is limiting what its employees gather in the first place. A jurisdiction that says “our officers may not share immigration status information they already have with federal authorities” is doing something 1373 forbids. The wording of a local policy often decides whether it is lawful.1Office of the Law Revision Counsel. 8 USC 1373 – Communication Between Government Agencies and the Immigration and Naturalization Service
What Counts as “Citizenship or Immigration Status”
The information covered by Section 1373 is narrower than most people assume. The statute reaches a person’s legal classification under federal immigration law. It does not reach every piece of information that might help federal agents find or arrest someone, such as a home address, work schedule, or scheduled release date from a local jail.
The Ninth Circuit relied on that limit when it rejected the federal government’s challenge to California’s SB 54. That state law restricted local law enforcement from sharing certain personal information with federal immigration authorities while still allowing the sharing of immigration status itself. The court held the arrangement consistent with Section 1373, reasoning that the statute covers only citizenship or immigration status and does not extend to other categories of personal information.2United States Courts. United States v State of California
Detainers Are a Separate Question
Refusing to honor ICE detainers is often lumped together with Section 1373, but the two issues are distinct. A detainer asks a local jail to hold a person past their scheduled release so ICE can pick them up. That is a request to take custodial action, not to share information. The Third Circuit and other federal courts have confirmed that detainers are voluntary requests local agencies are free to disregard.3Justia Law. Galarza v Szalczyk, No. 12-3991 (3d Cir. 2014)
Multiple courts have also held that holding someone on a detainer without a judicial warrant can violate the Fourth Amendment, because it functions as a new arrest without probable cause. That constitutional exposure gives jurisdictions an independent reason to decline detainers that has nothing to do with information sharing under Section 1373.
How the Statute Is Enforced
Section 1373 contains no penalties. There is no fine, no criminal sanction, and no enforcement mechanism in the statute itself. The federal government’s main lever has been to condition federal grant funding on certification of compliance.
The certification requirement for Byrne JAG grants, the primary federal law enforcement grant program, predates the first Trump administration. The Office of Justice Programs determined in 2016 that Section 1373 was an applicable federal law under the Byrne JAG authorizing legislation and began requiring applicants to certify compliance.4U.S. Department of Justice. Backgrounder on Grant Requirements In 2017, the DOJ layered on additional conditions, including giving ICE access to detention facilities and providing 48 hours’ notice before releasing someone subject to a detainer.
The Third Circuit struck those added conditions down in 2019, ruling that Congress had never authorized the Attorney General to impose them. The court decided the case on statutory grounds and did not reach the constitutional question, though the district court below had ruled that Section 1373 itself violates the Tenth Amendment.5Justia Law. City of Philadelphia v Attorney General United States, No. 18-2648
Is Section 1373 Even Constitutional?
The Tenth Amendment’s anti-commandeering doctrine forbids the federal government from forcing states to enact or enforce federal regulatory programs. Whether Section 1373 crosses that line is unsettled.
The Second Circuit upheld the statute in 1999, reasoning that it does not compel state action but only prevents governments from gagging their own employees.6Justia Law. City of New York v United States, 179 F.3d 29 (2d Cir. 1999) Nearly twenty years later, the Supreme Court decided Murphy v. NCAA, which strengthened anti-commandeering by holding that Congress “may not simply commandeer the legislative process of the States by directly compelling them to enact and enforce a federal regulatory program.”7Supreme Court of the United States. Murphy v National Collegiate Athletic Assn Some lower courts and legal scholars read Murphy to mean that telling a state legislature what policies it may not adopt about its own employees’ communications is itself a form of commandeering.
The Supreme Court has not directly ruled on Section 1373. Until it does, constitutionality depends on which federal circuit a jurisdiction sits in.
Where Things Stand in 2025 and 2026
On January 20, 2025, President Trump signed an executive order directing the Attorney General and the Secretary of Homeland Security to evaluate withholding federal funds from sanctuary jurisdictions, and instructing DHS to issue guidance ensuring “maximum compliance” with Section 1373. On February 5, 2025, the Department of Justice issued a memorandum requiring any jurisdiction applying for certain DOJ grants to certify compliance with Section 1373(a). The memorandum defined sanctuary jurisdictions broadly to include any state or locality that refuses to comply with Section 1373, refuses to certify compliance, or willfully fails to comply with other applicable federal immigration laws.8U.S. Department of Justice. Sanctuary Jurisdiction Directives
Several jurisdictions sued. In April 2025, a federal judge in San Francisco issued a preliminary injunction blocking the administration from cutting funds to sanctuary jurisdictions. As of January 2026, the litigation remained active, with the court denying the administration’s motion to dismiss and finding that the president may have overstepped his authority by creating new funding conditions without congressional approval.
For local governments, the practical picture has not changed much since 2017. The risk of losing federal funding is real but has repeatedly been blocked by courts. The risk of honoring detainers without judicial warrants has produced actual liability in multiple circuits. Policies drafted between those two pressures tend to look the same: limit what officers collect, share immigration status when asked, decline to hold people past their release without a warrant, and stay silent on the categories 1373 does not reach.