In San Francisco there is a policy left over from the old days that allows a person operate as a Patrol Special. Basically they can set up a security company in a neighbor and solicit business from businesses and resident to provide supplemental security. It is in addition to police protection. Slater inherited such a company from his brother.
Serving San Francisco Neighborhoods since 1847 Dating back to the gold rush days, the San Francisco Patrol Special Police has carved a unique niche in the history of San Francisco law enforcement by providing neighborhoods with supplementary police patrol. Formed in 1847 by merchants to combat the insurgence of Barbary Coast outlaws, the Patrol Special Police was incorporated into the city’s charter in 1935. Over the years, Patrol Special Officers have received many commendations for their exemplary service and dedication to the City of San Francisco. http://www.sfpatrolspecpolice.com/history.htm