California Business & Professions Code §§ 480 et. seq. generally govern the use of criminal records in granting, denying, and suspending an occupational license. Cal. Bus. & Prof. Code § 480(a)(3) states that:
The board may deny a license pursuant to this subdivision only if the crime or act is substantially related to the qualifications, functions or duties of the business or profession for which application is made.
Currently, the burden of proof lies with the applicant to disprove substantial relationship between the crime and the qualifications, functions, or duties of the licensed occupation. In October of 2007, Governor Schwarzenegger vetoed AB 1025, which would have shifted the burden of proof to the licensing board to meet the substantial relationship test when the applicant has obtained expungement and/or Certificate of Rehabilitation.
For more detailed analysis of each occupational licensing agency's policy in California, refer to Jonatha Cantu & Joan Petersilia, Working Paper: A Survey of Employment Sanctions Imposed Upon Ex-Offenders by California Law, Jan. 27, 2006.