Republicans in Congress are taking aim at four cities — often called “sanctuary cities” — over their policies limiting cooperation with immigration enforcement with a hearing this week that comes as President Donald Trump presses ahead with his campaign of mass deportations. Mayors Michelle Wu of Boston, Brandon Johnson of Chicago, Mike Johnston of Denver and Eric Adams of New York are set to appear Wednesday in front of the House Committee on Oversight and Government Reform. There’s no strict definition for sanctuary policies or sanctuary cities, but the terms generally describe limited cooperation with Immigration and Customs Enforcement. ICE enforces U.S. immigration laws nationwide but seeks state and local help, particularly for large-scale deportations, requesting that police and sheriffs alert them to people it wants to deport and hold them until federal officers take custody. But some cities and states say cooperating with ICE means victims of crime and witnesses who aren’t in the U.S. legally won’t come forward. And, to varying degrees, officials argue that they want their localities to be welcoming places for immigrants. Courts have repeatedly upheld the legality of most sanctuary laws. But Trump administration officials have targeted sanctuary policies right out of the gate in his second term, seeing them as a key impediment to deporting people in the large numbers he wants. The administration has sued Chicago and Illinois as well as New York state over various immigration laws. Here’s a look at the immigration policies and migration trends of the cities whose mayors will appear Wednesday: Boston The city’s Trust Act generally restricts how much the police can cooperate with ICE, although it does allow some cooperation with a division called Homeland Security Investigations when it comes to such issues as combating human trafficking or drug and weapons trafficking. The city also must follow a 2017 ruling by the state’s highest court that forbids Massachusetts authorities from holding a person otherwise entitled to release from custody based solely on a federal request. Those requests, called detainers, typically ask federal, state, local and tribal law enforcement agencies to give at least 48 hours’ notice before suspected immigrants are released from jail — or to hold them for up to 48 hours after they would normally be released so ICE can pick them up. Otherwise, ICE must go out into the community to arrest them. Trump’s border czar, Tom Homan, hammered Boston’s police commissioner and promised to go to Boston and “bring hell” with him. That has not sat well in Boston. Wu, a Democrat up for reelection this year, said that it was “clueless” and “insulting” for Homan to attack the police commissioner and that she wants Boston be a welcoming place for immigrants. Suffolk County District Attorney Kevin Hayden said handing over defendants makes it harder to gain cooperation from immigrants when investigating crimes. Chicago Chicago has some of the country’s strongest immigrant protections, barring cooperation between federal agents and city employees, including police. The nation’s third-largest city became a sanctuary location in the 1980s and has amped up its policies multiple times since. That includes a 2012 ordinance that bars federal agents from accessing city resources in assisting with immigration operations. City officials beefed up protections after Trump first took office in 2017 and again in 2020, when it required police to document requests for assistance from federal agents. Illinois also has protections allowing anyone, regardless of immigration status, to get a driver’s license. Mayor Brandon Johnson, […]