Proponents of "sanctuary cities", like Kenney, say they create trust between police and immigrants, who otherwise might be afraid to report crimes.
The sanctuary jurisdictions say they are following the law, which says local authorities can not prevent information exchange with federal immigration agents about people's immigration status.
In a letter issued Thursday, the DOJ warned the city it has "laws, policies or practices" that violate a federal statute requiring local governments to comply with federal immigration officials in deporting suspected undocumented immigrants in local jails.
Offending cities and states stand to lose money from the Edward Byrne Memorial Justice Assistance Grant (or JAG grant), which provided Philadelphia with $1.6 million in 2016 to spend on police overtime, training, equipment, courtroom technology and other aspects of the criminal justice system. Though this rule is aimed at barring questions about immigrants' legal status, DOJ says it could be interpreted to bar NYPD members from requesting immigration info from federal immigration officers, which would be illegal.
DOJ in its recent announcement also determined that Milwaukee County, Wisc., Clark County, Nev., Miami-Dade County, Fla., and the state of CT are in compliance with Federal law and are not guilty of sanctuary cities violations.
The DOJ claims that an NOPD policy "may" violate a federal statute that deals with how local governments provide information to federal immigration officials "depending on how your jurisdiction interprets and applies them", Alan Hanson, acting assistant attorney general wrote. ". We urge jurisdictions to not only comply with Section 1373 but to establish sensible and effective partnerships to properly process criminal aliens".
Landrieu has denied that New Orleans is a sanctuary city and has disputed prior findings from the DOJ with letters that he says prove the city is in compliance with federal law.
"Chicago will not be blackmailed into changing our values, and we are and will remain a welcoming city", Mayor Rahm Emanuel said at a press conference announcing that suit.
Some of the disputes concern the jurisdictions' compliance with U.S. Immigration and Customs Enforcement "detainer" requests, sent to local authorities when ICE wants to hold people in custody up to 48 hours and beyond when they are supposed to be released so that immigration officials can pick them up.
Chicago sued the federal government in August over the threats of funding cuts being made by Justice Department.