CA Gov't Code Section 1365

It is unlawful for any person having the power of removal from office of any officer to remove or threaten to remove the officer from his office because the officer, in the appointment of any person to a position of public trust under himself, refuses to require any additional test or qualification, other than the oath prescribed by this article and tests and qualifications provided for under civil service and retirement laws, as a condition of permitting the appointee to enter upon or remain in the position of public trust.