California State Assemblyman Tom Ammiano representing San Francisco has co-sponsored a bill called "The Trust Act" (AB 1081) The Trust Act is a bill which would allow counties to opt-out from full participation in federal enforcement program called "Secured Communities," also known as S-Comm.
Currently anyone who is arrested and booked has their fingerprints taken. The "Secure Communities" program allows the prints to not only be checked against FBI criminal history records but also against Department of Homeland Security's (DHS) immigration records. If the fingerprints match DHS records, Immigration Customs and Enforcement ("ICE") determines if they should become involved in "enforcement action" - another name for deporting the person.
According to Assemblyman Ammiano's discussion of the bill on his website, ICE has misled the public about Secure Communities, "whose real focus is more spin than safety. In fact seven in ten Californians deported under S-Comm had committed no crime or were picked up for minor offenses like traffic violations."