FIRST ON FOXImmigration and Customs Enforcement (ICE) predicted in January that there would be a 50% reduction of arrests of illegal immigrants if new guidance that severely limits ICE arrests was enforced -- a prediction that ultimately proved to be accurate, as arrests plunged a month later.

The Department of Homeland Security (DHS) issued interim guidance on Inauguration Day, which narrowed immigration enforcement priorities to illegal immigrants who were: a national security threat; recent border crossers; or convicted of an "aggravated felony." It also included a pause on deportations, which was later blocked by a judge in response to a lawsuit from Texas.

DHS LIMITS ICE ABILITY TO ARREST ILLEGAL IMMIGRANTS NEAR COURTHOUSES

In February, ICE issued its own version of that guidance, with the same narrowed priorities and also requiring ICE agents to seek preapproval from a superior if they wanted to arrest an illegal immigrant who did not meet that criteria.

However, in calculating what that policy would mean for the agency, a Jan. 27 email by ICE’s Enforcement and Removal Operations’ acting executive associate director warned that the department ran data based on the new DHS guidance, and predicted that "book-ins" would plunge.

"Rough estimate is book-ins would be reduced by 50% of historical numbers and the vast majority of book-ins would come from [Customs and Border Protection] transfers," the email says.

A book-in is an individual entering ICE custody from a single arrest by CBP or ICE. The fact that most would come from Border Patrol transfers, rather than enforcement, emphasized how dramatically ICE’s own enforcement would be hampered by the guidance.

ICE ARRESTS PLUMMET IN FEBRUARY AS BIDEN ADMINISTRATION TIGHTENS RULES

The prediction turned out to be on point. ICE arrested just 2,374 illegal immigrants in February, down by more than 50% than the 5,882 arrested in January and 6,680 in December.

The email was obtained by Arizona Attorney General Mark Brnovich’s office as part of a court-ordered discovery process in response to a lawsuit in March by Arizona and Montana that seeks to block that guidance.

The states argued that the guidance will lead to an increase in criminals, drugs and COVID-19 in their states and is in violation of federal law.

ARIZONA, MONTANA SUE TO BLOCK DHS RULES THAT WOULD LIMIT ICE ARRESTS 

Separate data obtained by Brnovich’s office as part of the discovery show that ICE identified thousands of illegal immigrants with criminal convictions who would not be a priority for enforcement if the guidance was applied. Those marked as having "no known priority" includes more than 3,000 with assault convictions, more than 4,000 with drugs convictions including others with convictions for sex offenses (225), homicide (85) and weapons offenses (503.)

"The DHS records we have obtained convey a shocking disregard for the safety of American communities by the Biden Administration," said Attorney General Mark Brnovich in a statement. "The Biden administration and its radical allies are effectively abolishing ICE through administrative acts."

DHS provided more than 5,000 pages of records as part of the discovery, but Brnovich’s office said that just 170 pages were not redacted.

The controversial guidance is part of a broader rollback of ICE enforcement by the Biden administration, which has sought to take a radically different approach from the Trump administration. Acting ICE Director Tae Johnson claimed in February that the guidance would make ICE more efficient, while officials emphasized the guidance did not completely rule out anyone from enforcement action.

"By focusing our limited resources on cases that present threats to national security, border security, and public safety, our agency will more ably and effectively execute its law enforcement mission," Johnson said in a statement.

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This week, the Biden administration announced that it was slapping limits on ICE’s ability to arrest illegal immigrants in or near courtrooms. 

Meanwhile, the White House announced President Biden had tapped Ed Gonzalez, who was a staunch opponent of ICE raids during the Trump administration, to lead the agency.