President Donald Trump signed an executive order on April 28, 2025, that demands the U.S. attorney general, in coordination with the secretary of Homeland Security, publish a list of cities and states that obstruct the enforcement of federal immigration laws, with the purpose of protecting Americans from “criminal aliens.”

Philadelphia will likely end up on the list.

Philadelphia is what’s known as a sanctuary city. While the term has no fixed definition, it usually refers to a city that has declared its refusal to cooperate – or even works at odds – with federal immigration enforcement.

As a law professor at Temple University in Philadelphia, where I supervise students who represent low-wage immigrant workers, I know that sanctuary policies can slow the federal immigration enforcement system.

But the bottom line is that federal immigration officers – usually U.S. Immigration and Customs Enforcement – can still carry out deportations in a sanctuary city.

Further, there is no question that localities such as Philadelphia can legally decide not to cooperate with federal immigration enforcement. Cities, like states, have constitutional protections against being forced to administer or enforce federal programs. The Trump administration cannot force any state or local official to assist in enforcing federal immigration law.

What remains to be seen is what, if any, action the administration will take against those jurisdictions that end up on their list of sanctuary cities.

Philly’s sanctuary policies

My work has involved researching sanctuary policies as well as how often ICE relies on local law enforcement to help identify and turn over immigrants.

Philadelphia’s various sanctuary policies break that connection and leave ICE to its own devices. They also signal to immigrants that the city is not in the business of federal immigration enforcement. Research shows this helps immigrants feel safer to access public benefits and services such as getting care at a community health center or calling the........

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