The legal limits of Trump’s crackdown on sanctuary cities like Philadelphia

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 police without fear of immigration consequences.

Philadelphia’s most notable sanctuary policy, an executive order signed by then-Mayor Jim Kenney in January 2016, is its refusal to have its jails honor ICE detainers or requests for release dates. An ICE detainer is a voluntary request asking local officials to hold an immigrant, who is otherwise going to be released, for an additional 48 hours so ICE can pick them up.

Failing to honor ICE detainers disrupts the deportation pipeline and makes ICE’s job more difficult.

Another key Philadelphia sanctuary policy dates back to 2009 and was signed by then-Mayor Michael Nutter. It makes clear that city officials do not police immigration. Not only are all city workers – including police, firefighters and behavioral health workers – prohibited from asking about immigration status in most situations, but police are specifically directed not to stop, arrest or detain a person “solely because of perceived immigration status.”

Yet there is no way to enforce these sanctuary policies. Under these laws, city officials who violate them do not face consequences. Compliance relies on a commitment from officials who believe that following these policies is the right thing to do.

Philadelphia has also acted in other ways to break the link between the city and immigration enforcement.

Since 2017, Philadelphia jails have had a protocol that discourages ICE from interviewing immigrants held in jail. Prior to providing ICE with access to such individuals, the jails must first send a consent form to an immigrant to inform them of their right to decline an ICE interview.

In 2018, Philadelphia ended ICE’s access to the city’s preliminary arraignment reporting system used by the Philadelphia Police Department and district attorney’s office. The city said it terminated its database-sharing contract with ICE given the “unacceptable” way the agency used the system, which “could result in immigration enforcement action against Philadelphians who haven’t been arrested, accused of, or convicted of any crime.”

While these policies cannot protect Philadelphia residents who have been arrested by ICE, the lack of help of local officials will make it more difficult for the administration to deliver on its promise to deport a record number of immigrants.

Sanctuary campuses and churches

Apart from the city itself, other public and private institutions within Philadelphia have created sanctuary spaces.

In June 2021, the School Board of Philadelphia adopted a sanctuary resolution as part of an effort to create welcoming schools for immigrant children. In January 2025, the Philadelphia School District reaffirmed its commitment.

Under the first Trump presidency, religious institutions, such as the Germantown Mennonite Church in Northwest Philly and the Tabernacle United Church in West Philly, provided sanctuary inside their churches to immigrants who had received final orders of deportation from ICE.

The University of Pennsylvania declared itself a sanctuary campus in 2016 but is currently shying away from that label while faculty, staff and students demand that the university clarify its policies on immigration enforcement.

Since 2011, ICE has had a “sensitive locations” memo that disfavors but does not entirely prohibit immigration enforcement in places of worship, as well as hospitals and schools. The Biden administration strengthened the “sensitive locations” memo in 2021. Trump rescinded the memo during his first month in office.

Retaliation against sanctuary cities

From the viewpoint of the Trump administration, state and local officials who defy the enforcement of immigration law are engaged in “a lawless insurrection” that creates public safety and national security risks.

Despite the administration’s strong rhetoric about the “criminal alien,” 46% of people currently held in immigration detention have no criminal record, according to the Transactional Records Access Clearinghouse at Syracuse University. Many others have minor offenses, including traffic violations.

The executive order vows to terminate federal grants and pursue all enforcement measures to bring such jurisdictions “into compliance with the laws of the United States.”

Such terminations may not be legal.

On April 24, 2025, a federal judge enjoined language in an earlier executive order directing the government to take action against sanctuary cities to ensure that they do not receive access to federal funds.

Past instances to pull federal funding from Philadelphia because of its sanctuary city status have also failed. The first Trump administration was unsuccessful at terminating a US$1 million federal grant to Philadelphia after the city sued and won in federal court in 2017.

The executive order also makes legally questionable claims that state and local officials who follow their sanctuary policies are engaging in criminal activity, such as the obstruction of justice, unlawful harboring or activities that violate federal RICO law. Regardless, the administration may still choose to pursue high-profile prosecutions of state and local officials.

The federal government’s efforts to punish sanctuary cities will undoubtedly be mired in legal challenges across the country. Yet Philadelphia officials must still decide in this moment whether to stand strong with the city’s current sanctuary policies. City Council member Rue Landau has been outspoken about maintaining Philadelphia’s sanctuary status to ensure that public resources will never be used to support federal deportation efforts. But Mayor Cherelle Parker has not committed to strengthening or even ensuring the city’s sanctuary protections.

According to The Philadelphia Inquirer, the same day Trump signed the executive order, Parker reiterated that Philadelphia still operates under its 2016 sanctuary policy. However, she did not use the term “sanctuary city,” the Inquirer noted, and she “said she would not comment in more detail until Trump makes concrete moves that affect Philadelphia.”

This is an updated version of a story originally published on December 18, 2024.

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Jennifer J. Lee does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.