California will ban the use of for-profit, private detention facilities, including those under contract to the federal government to hold immigrants awaiting deportation hearings, under a bill that Gov. Gavin Newsom said Friday that he had signed.

The Democratic governor said the measure helps fulfill a promise he made to end private prison use, which he said contributes to over-incarceration and does “not reflect our values.”

The state’s prison system was already phasing them out, despite having to comply with an inmate population cap imposed by federal judges.

Immigrant advocates have praised the bill authored by Democratic Assemblyman Rob Bonta, which they said would put an end to almost all immigration detention in California in the next few years. “We are sending a powerful message that we vehemently oppose the practice of profiteering off the backs of Californians in custody,” Bonta said.