By John Byrne and Hal Dardick

Mayor Rahm Emanuel's Law Department on Monday filed its much-touted lawsuit against President Donald Trump's Justice Department over its effort to withhold some grant funding from so-called sanctuary cities.

Emanuel wants a federal judge to block the Trump administration from enforcing its new policy, which would affect not just Chicago, but other major U.S. cities like New York and San Francisco. U.S. Attorney General Jeff Sessions' funding decision also would affect Cook County, which also holds sanctuary status and operates the largest single-site jail in the country.

The Justice Department quickly fired back in an emailed response that notes last year more people were killed in Chicago than New York and Los Angeles combined. "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," the response stated.

Trump has long maintained that illegal immigration fuels crime, an assertion that critics say is not backed by statistics that show immigrants in the country without the required permission are less likely to commit crimes than U.S. citizens and legal residents. And Emanuel in a rare Sunday news conference maintained Trump's policy would damage efforts to tamp down crime, because people in the city without documentation would then be afraid to cooperate with police.

Emanuel said Sessions' new policy is unlawful and unconstitutional. He also called it "the camel's nose under the tent," contending it was an effort to set precedent that could result in the withholding of further grant money.

This year, the city was counting on receiving $3.2 million from the grants in question, a relatively miniscule portion of the city's overall $9.8 billion budget.

Under the new Justice Department policy, contained in conditions attached last week to applications for Edward Byrne Justice Assistance Grant funding, the city would have to meet three conditions to receive funds that the city has used in the past to buy police vehicles and other equipment.

The conditions: sharing immigration status information with federal officials enforcing deportation laws, providing unlimited police station access to those officials, and giving the officials 48-hours notice of an arrested person's release in cases of potential immigration violations.

"These new conditions -- which would give federal officials the power to enter city facilities and interrogate arrestees at will and would force the city to detain individuals longer than justified by probable cause, solely to permit federal officials to investigate their immigration status -- are unauthorized and unconstitutional," the lawsuit states.

"These new conditions also fly in the face of longstanding City policy that promotes cooperation between local law enforcement and immigrant communities, ensures access to essential city services for all residents, and makes all Chicagoans safer," the suit adds. "Neither federal law nor the United States Constitution permits the attorney general to force Chicago to abandon this critical local policy."

Under the city's welcoming city ordinance, which sets its status as a sanctuary city, bars police from providing federal Immigration and Customs Enforcement officials access to people in local custody unless they are wanted on a criminal warrant or have serious criminal convictions. It also prohibits allowing ICE agents to sue police facilities for interviews or investigations, and bars on-duty officers from responding to ICE questions or talking to ICE officials prior to a person's release from custody.

After the lawsuit was filed Monday, city Corporation Counsel Ed Siskel said the city will next file a motion for a preliminary injunction prohibiting the Justice Department from imposing the new rules. He said the city will ask the court to set a briefing schedule so a ruling can be issued before Sept. 5, the deadline for the Byrne grant applications.

Siskel said the Byrne grant is "critical" for the city's public safety, even though it brings in such a small amount of money in the context of the full municipal budget it would hardly register as a blip if the city didn't get it. "We are at a time when every bit counts and every resource matters in this fight," he said. "In addition, we are bringing this legal challenge because the rhetoric and the threats from this administration, embodied in these new restrictions placed on public safety grant funds, are breeding a culture and a climate of fear within the communities in our city."

Emanuel's lawsuit was filed three days after he telegraphed that it was coming during an interview with a veteran radio reporter. In addition to the Sunday news conference, Emanuel appeared on CNN's "Newsroom" show on Monday morning to tout the case.

The mayor has been railing against Trump's tough-on-immigration policies since the last year became the presumptive Republican nominee. It's a position for Emanuel that plays well politically in largely Democratic Chicago.

Emanuel also backed successful efforts to strengthen the city's welcoming city ordinance, create a legal fund to assist immigrants threatened with deportation and start developing a municipal ID program aimed mostly at helping immigrants without documentation make their way in the city.

"This is not about politics, this is about protecting the constitutional rights of the residents of the city of Chicago and standing up for our values as a welcoming city," Siskel said.

(c)2017 the Chicago Tribune

*This story has been updated.