Here's what sanctuary cities like S.F. can do to protect immigrants from ICE — and what they can't

San Francisco Chronicle​

12-07-2025

Since 1989, San Francisco has declared itself a 'sanctuary city' and put policies in place that limit its cooperation with what is now Immigration and Customs Enforcement.
As the Trump administration has significantly escalated its efforts to deport undocumented immigrants in recent months, there has been widespread confusion about what the term 'sanctuary' means — and what authority cities do or don't have to resist federal immigration enforcement efforts.
San Francisco, and the hundreds of sanctuary cities like it across the country, do not have to cooperate with ICE agents and federal immigration authorities. But neither can they interfere with or impede federal agents carrying out federal law. Although the distinction at times may seem arbitrary, it is one well established in the law.
Cities do not — and cannot legally — provide literal sanctuary to those that ICE wants to apprehend. Rather, in a sanctuary city, its police, its teachers and its health officials do not turn over people to ICE.
That is a policy that makes great sense. San Francisco and other cities rightly worry that if police turned people over to ICE, then victims of crime and witnesses would be much less likely to come forward. If school officials cooperated with ICE, parents would be less likely to send their children to school. If health officials helped enforce immigration laws, sick people would be less likely to seek treatment.
Refusing to cooperate with federal agents in this manner is protected by the U.S. Constitution. The Supreme Court has been clear that the federal government cannot commandeer state and local governments to carry out federal mandates.
For example, in the 1997 case Printz v. the United States, the court declared unconstitutional a provision of the Brady Handgun Control Act that required state and local law enforcement departments to conduct background checks before issuing permits for firearms. The court said that the federal government cannot conscript state and local governments and compel them to enforce federal law. In a majority opinion by Justice Antonin Scalia, the court held that such commandeering violates the 10th Amendment to the Constitution.
That said, Congress can try to induce state and local governments to act by putting conditions on federal grants. However, the law is well established that it is for Congress — by way of a federal statute — to set conditions; presidents cannot do so on their own.
Thus far, Congress has not conditioned the distribution of federal law enforcement money on state and local governments cooperating with ICE. The Trump administration cannot add requirements not found in the federal spending law.
That hasn't stopped President Donald Trump from trying, of course. During Trump's first term, the Justice Department attempted to withdraw federal law enforcement funds from cities that did not cooperate with ICE. However, in a lawsuit filed by San Francisco, the U.S. Court of Appeals based in San Francisco ruled in 2018 that the president did not have the legal authority to withhold the funds from cities.
Also, the Supreme Court has been clear that the federal government cannot coerce state and local action by withholding federal funds. In 2012, in National Federation of Independent Business v. Sebelius, the court declared unconstitutional a provision of the Patient Protection and Affordable Care Act that required state governments receiving Medicaid funds to provide coverage to those within 133% of the federal poverty level. States that did not comply would lose all federal Medicaid funds. The court said that this was 'dragooning' the states, impermissibly commandeering them to comply with a federal mandate.
The same ruling would apply if the federal government tried to coerce local governments into cooperating with ICE.
The current Trump administration has, of course, threatened local government officials who don't cooperate with federal immigration officials. Just a day after Trump's inauguration in January, acting Deputy Attorney General Emil Bove wrote a memo to the Justice Department calling on U.S. attorneys to prosecute state and local officials who do not cooperate with deportation efforts. President Trump also has expressed this, saying that state and local officials face prosecution for failing to assist his immigration policies. But such prosecutions would be unconstitutional: State and local officials do not have to cooperate with the federal government.
On June 30, the Trump administration filed a lawsuit against the city of Los Angeles for its refusal to cooperate with ICE. Los Angeles does not allow city resources to be used to assist immigration enforcement, and that policy should prevail in this lawsuit. A city gets to decide for itself how it will spend its budget and what its officers may do. The federal government cannot constitutionally force a municipality to use its resources and its personnel to assist in the enforcement of federal law; that is impermissible commandeering.
But neither can cities act to obstruct ICE and federal immigration officials. Los Angeles, San Francisco and any other city cannot provide shelter to those ICE wants to apprehend. Nor can they prevent ICE agents from entering buildings or arresting people. Active interference with ICE agents can be punished.
Understandably, neither side is entirely happy with these principles. The Trump administration wants to force state and local officials to assist ICE. Opponents of Trump's policies want cities to do even more to provide protection and thwart ICE.
But the law — that San Francisco and other cities don't have to cooperate with ICE but cannot actively obstruct it either — makes great sense. The federal government can enforce federal law as it sees appropriate, but it can't force state and local governments to help. State and local governments can choose not to assist ICE, but they can't obstruct it.
Erwin Chemerinsky is the dean and the Jesse H. Choper Distinguished Professor of Law at the UC Berkeley School of Law.