In California, employers generally cannot require employees or job applicants to take a lie detector test. This protection comes from both state and federal laws. Under California Labor Code Section 432.2, employers are prohibited from making polygraph test a condition of hiring or continued employment. Employees can voluntarily agree to take one, but only if they are fully informed of their rights in writing. 

Similarly, the federal Employee Polygraph Protection Act (EPPA) bans most private employers from using lie detector tests for hiring, firing, or disciplinary decisions, with limited exceptions for security related jobs or theft investigations. Public sector employers, including federal, state, and local government agencies, are generally exempt from these restrictions and may require polygraph tests under specific conditions.