At-will employment does not mean that a California employer has an unlimited right to fire their workers. There is such as thing as crossing a line when terminating an employee. Companies still must follow federal laws and the employment contracts that they sign. Otherwise, they can be sued for wrongful termination.
Employment discrimination cases
Wrongful termination can arise in a number of contexts. One is when the employer acts in a discriminatory manner based on a number of protected classes that include race, religion, gender and ethnicity. Here, you would contest the wrongful termination by filing a complaint with the Equal Employment Opportunity Commission. Eventually, either the EEOC would file a lawsuit on your behalf, or you would file one yourself.
A firing can be a breach of contract
A wrongful firing could also happen from a contractual standpoint. You may have an employment agreement that either guarantees you employment under certain circumstances or requires the employer to follow certain procedures before they fire you. This could create a right of employment that lessens the at-will nature of your employment. Here, you would need a contractual clause in your employment agreement that says that you could only be fired for cause.
There are other specific actions that employers cannot fire you for. For example, they cannot retaliate against you if you are a whistleblower. If you report certain activities at work, the law gives you some protections.
Wrongful termination claims are not always easy cases. The employer has every motivation to fight, but this is also balanced with some caution because they may not want certain facts out in public. The first thing you should do if you think that you have been wrongfully fired is to hire an employment law attorney. The lawyer could educate you about the process and let you know what type of proof you need to win the lawsuit. They could also engage your employer to either negotiate a settlement agreement or win you reinstatement to your job.