CHICAGO (AP) — A federal appeals court blocked the immediate release of hundreds of immigrants detained during a Chicago area immigration crackdown in a split decision Thursday that also allowed the extension of a consent decree outlining how federal immigration agents can make warrantless arrests.

The 7th U.S. Circuit Court of Appeals heard arguments last week regarding a 2022 agreement governing how U.S. Immigration and Customs Enforcement (ICE) can arrest immigrants aside from specifically targeted individuals. The consent decree has come under scrutiny amid increased immigration enforcement activities that have resulted in over 4,000 arrests in the Chicago area.

Last month, U.S. District Judge Jeffrey Cummings ordered the release of more than 600 immigrants on bond, claiming that the government had violated the agreement. The appeals court, however, has paused this release. Currently, approximately 450 immigrants remain in custody, as stated by attorneys involved in the cases.

In a 2-1 opinion, the appeals court determined that Cummings overstepped his authority by ordering the blanket release of detainees without reviewing each case individually. The ruling emphasized that the consent decree carefully delineates the powers of the district judge in balancing immigration enforcement and public safety. Additionally, the court criticized the Trump administration for categorizing all immigrant arrestees as mandatory detention cases.

Plaintiffs' attorneys expressed disappointment but acknowledged that the court upheld the agreement's extension, which mandates that ICE provide documentation for every arrest made. This ruling aligns with decisions in other states, including Colorado, where judges have also sought to limit warrantless arrests.

Attorneys argued for an expedited decision as many detainees face deportation without understanding their rights or options. The affected individuals were primarily arrested during the summer through the early weeks of 'Operation Midway Blitz' immigration efforts in the fall. Legal representatives have information on hundreds more individuals they believe were also improperly detained.

“We will work tirelessly to ensure that people who were unlawfully arrested will be able to return to their families and communities as soon as possible,” stated Keren Zwick from the National Immigrant Justice Center.

A request for comment from the Department of Homeland Security was not immediately answered. The consent decree, which expired earlier this year, has been extended until February, following attempts by the federal government to challenge the extension. Originally agreed upon between immigrant-rights groups and the federal agency following a lawsuit over 2018 immigration sweeps, the decree affects individuals arrested in Illinois, Indiana, Kansas, Missouri, Kentucky, and Wisconsin.