i'm not trying to argue or prove you wrong desert, but i was still curious and went ahead and googled it.. seems they take the pools from several sources, including voter reg. and drivers licenses ...
Jury Duty
Lists of Potential Jurors
Jurors names are selected at random from lists of registered voters and individuals who have a driver's license or identification card issued by the California Department of Motor Vehicles. You are qualified for jury service if you:
Are a U.S. Citizen
Are 18 years or older
Have sufficient knowledge of the English language
Are a resident of the county that summoned you
Are not currently serving on a grand jury or trial jury
Are not under a conservatorship
Have no felony convictions
http://www.placer.courts.ca.gov/jury/jury_general_potential-jurors.html