More than 30 immigrants in the country illegally were freed from Maricopa County jails over the last four days after Sheriff Paul Penzone made a change in one of his policies.

The new rule announced abruptly on Friday shortens the length of time the jail will perform courtesy holds for Immigration and Customs Enforcement.

Maricopa County Attorney Bill Montgomery says his office advised the sheriff to make the change after determining that holding immigration detainees for up to 48 hours after their scheduled release was unconstitutional.

"It’s very clear that the Fourth Amendment does not allow a local law enforcement official to detain someone longer than what’s necessary to process a state court-ordered release,” Montgomery said.

The Sheriff’s Office says the immigrants went free because federal authorities declined to pick them up after the inmates became eligible for release from jail on state charges.

ICE called the policy change unfortunate and says it has since arrested five of the freed immigrants.