A federal judge found Border Patrol agents engaged in "a pattern and practice" of violating people's constitutional rights, after they detained and arrested dozens in a Central Valley raid in January.

The ruling comes in response to the January immigration enforcement campaign known as "Operation Return to Sender."

A federal judge in California has barred Border Patrol agents from arresting someone suspected of living in the U.S. illegally unless they have a warrant or a reason to believe the person might flee before a warrant can be obtained.