The U.S. government filed a lawsuit Thursday challenging the sanctuary policies in Illinois and Chicago, arguing they are unlawfully interfering with federal authorities’ ability to arrest and deport illegal immigrants.

Justice Department lawyers said the state and local policies go beyond noncooperation and “intentionally obstruct” the feds by restricting the flow of information.

State and local authorities not only refuse to hold deportation targets when requested, but also refuse to share information about their release from prisons and jails, preventing Homeland Security from being on hand to collect them, the federal government said.

The lack of cooperation has consequences, the Justice Department said, pointing to a migrant released from the Cook County jail in August despite a deportation detainer request from Homeland Security. In October the migrant was arrested for aggravated criminal sexual assault and abuse of a minor.

“The challenged provisions of Illinois, Chicago and Cook County law have the purpose and effect of making it more difficult for, and deliberately impeding, federal immigration officers’ ability to carry out their responsibilities in those jurisdictions,” Brett Shumate, acting assistant attorney general for the Civil Division, said in the new lawsuit.

It was filed in federal district court in northern Illinois.

The Washington Times has sought comment from the state and city.

The lawsuit is a definitive debut for Attorney General Pam Bondi, who was just sworn in a day earlier.

White House border czar Tom Homan had been warning sanctuary jurisdictions they would face legal consequences if they didn’t begin to cooperate, and suggested the government was waiting for Ms. Bondi to be in place.

The case challenges two state laws, the Way Forward Act and the Trust Act, as well as Chicago’s Welcoming City Act and Cook County’s Ordinance 11-O-73. They each work “interfere with and discriminate against” federal immigration enforcement, the U.S. government said.

Sanctuary jurisdictions justify their policies by saying they don’t want their law enforcement to be seen as entangled with federal immigration efforts. They say victims and witnesses within the immigrant community will be less likely to come forward, which would lead to more crime.

Mr. Homan on Thursday rejected that explanation.

“That is such crap,” he told reporters at the White House. “The victims and witnesses of that crime want that bad guy locked up, too.”

What is clear from the data is that sanctuary policies have made it tougher for the federal government to deport illegal immigrants. A single deportation officer sitting in a local jail could process multiple deportation targets a day, but once released, a single migrant can absorb weeks of manpower if ICE has to send a team to get him out in the community.

The number of sanctuary jurisdictions exploded during the first Trump administration as states and municipalities viewed the policies as a way of showing resistance to Mr. Trump.

Policies vary in their intensity, with some blocking all forms of communication and cooperation with federal immigration authorities. It’s so bad that U.S. Immigration and Customs Enforcement says some jurisdictions actually have a filter to refuse email communications from ICE.

Other jurisdictions will cooperate in cases where an immigrant has a serious criminal conviction, but refuse in other cases, including those where an illegal immigrant has been charged but not yet convicted.

Some jurisdictions will share information, such as release times, but won’t hold migrants beyond their regular release times.

The Illinois and Chicago sanctuary policies are on the stricter side.

• Stephen Dinan can be reached at sdinan@washingtontimes.com.

• Jeff Mordock can be reached at jmordock@washingtontimes.com.