Because California is an "at will" employment state, your employer can fire you for any reason except those that are against the law, such as mental or physical disability, pregnancy, race or religion. Clearly, you do have some protections. You cannot be terminated, for example, because of your gender or age. Also, it is unlawful for your employer to fire you because of your political affiliation.
In California, you cannot be terminated for exercising your legal and constitutional rights, such as engaging in free speech, joining a political group or association or reporting what you believe to be a violation of the law.
Protecting your rights
In many areas of the country, if you are working for a private company in a facility that is on private property belonging to your employer, your First Amendment rights are not protected; that is, your right to free speech is not absolute. However, there are four states - South Carolina, Louisiana, Connecticut and California - in which there are statutes that protect your right to express whatever political views you may hold. Your political outlook may be different than that of your employer and even most of your coworkers, but California law says you cannot be fired over it.
Sorting it out
Professionals who study employee rights say that even in large companies with efficient HR departments, many managers are not current on issues associated with the First Amendment. Therefore, if you express your political views, the manager may feel justified in terminating you, relying on the fact that California is an "at will" state. As a result, the company may find itself in legal hot water.
If you believe you were the victim of unlawful termination due to your political views, reach out to an attorney experienced with California employment law. You may be entitled to significant financial compensation as well as damages for emotional distress. Remember, you have rights, and your attorney will see that they are protected.