Deputy U.S. Attorney General Todd Blanche told top California leaders that they would be prosecuted if they arrested federal agents performing immigration raids.
Mr. Blanche said in the letter that arresting federal agents in the performance of their official duties would violate federal laws that prohibit interfering with and impeding immigration and other law enforcement operations.
The San Francisco district attorney said in an interview that she came up with the strategy after seeing federal agents repeatedly roughing up people in Los Angeles and Chicago.
The ability of states to arrest federal officers is murky, and without much legal precedent, according to the dean of University of California, Berkeley School of Law.