The city of Chicago will file a lawsuit against the Trump administration on Monday over Attorney General Jeff Sessions’ July announcement that the federal government would withhold certain grant funding from sanctuary cities.

“Chicago will not be blackmailed into changing our values, and we are and will remain a welcoming city,” Chicago Mayor Rahm Emanuel said at a press conference on Sunday announcing the lawsuit. “The federal government should be working with cities to provide necessary resources to improve public safety, not concocting new schemes to reduce our crime-fighting resources.”

The city argues that the threat to withhold funding violates the Constitution because it federalizes local law enforcement. Chicago Police Supt. Eddie Johnson also said at the press conference that he worries the DOJ policy could cause undocumented immigrants to fear reporting crimes.

Sessions announced in July that the Justice Department would bar cities from receiving grant money for local law enforcement unless the cities give federal law enforcement access to local jails and notify the federal government when the city is about to release an undocumented immigrant from jail.

In response to Emanuel’s announcement, the Justice Department called the Chicago lawsuit “tragic.”

“In 2016, more Chicagoans were murdered than in New York City and Los Angeles combined. So it’s especially tragic that the mayor is less concerned with that staggering figure than he is spending time and taxpayer money protecting criminal aliens and putting Chicago’s law enforcement at greater risk,” DOJ spokeswoman Sarah Isgur Flores said in a statement to the Chicago Sun-Times.