Hi, Jill's wife here. There is no specific law governing bathroom usage in the workplace in California. That said, gender identity and expression are expressly protected characteristics under the Fair Employment and Housing Act ("FEHA"), Cal. Gov't Code ยง 12940, which prohibits discrimination in employment based on various protected characteristics and for this purpose applies to any employer with five or more employees. So while there is no case law on point in this state that I am aware of, refusing to allow you to use the appropriate bathroom for your expressed gender likely constitutes unlawful discrimination under the FEHA. Your company may also have an Equal Employment Opportunity policy which, if at all up to date, should also list gender identity and expression as protected characteristics. So such a bathroom policy could run afoul of their own EEO policy too. You might ask how the company's position is consistent with FEHA and, if applicable, the company's EEO policy. Any issues, write back and we can find you a referral for employee-side labor counsel. Good luck!