Northern California:

Northern California Rapid Response & Immigrant Defense Network (NCRRIDN)
http://rapidresponse.sfbar.org/resources

Immigrant Legal Resource Center (IRLC)
https://www.ilrc.org

Southern California:

Coalition for Humane Immigrant Rights (CHIRLA)
http://chirla.org  

Central American Resource Center (CARECEN)
http://www.carecen-la.org