"At-will" employment means that, unless you have an agreement or contract with your employer for a specified term or may only be terminated "for cause," then you may be terminated for any (or no) reason at all, unless that reason is unlawful. On the same note, you may quit anytime you want, as well. An employer does not have to justify its actions, allow you to justify your actions, or even be fair or equitable in the process. You are, literally, at the will of your employer in this context.
Like any area of law, there are a few exceptions to the general rule that an at-will employee can be terminated for any reason. There are four main areas where the exceptions apply: (1) discrimination, (2) retaliation, (3) union workers, (4) implied contract. Keep in mind if you are considering bringing a suit under one of these exceptions that different time lines may apply, especially if the suit is based upon discrimination.
Discrimination Based on Protected Status
The main exception to an employee's at-will status occurs where the termination is based upon an employee's race, color, ethnicity, national origin, gender, age, or disability. The burden of proof is to show that you were treated less favorably than "similarly situated" employees that are not a part of your protected class (e.g. race, gender, age). If there is strong enough evidence to prove this discrimination was tied to your termination, then you may have a claim for wrongful termination. Both states and the federal government have discrimination laws. In California, the Department of Fair Employment and Housing is the appropriate entity to contact, whereas the Equal Employment Opportunity Commission is the federal equivalent. In either case, you need to first exhaust your "administrative" options first. This means, basically, that you need to file a complaint with the appropriate entity so that the entity can decide whether to investigate the complaint before you sue.
Retaliation for Protected Activity
Another common exception to an at-will employee's termination occurs when an employee is terminated out of retaliation. This occurs when the employer terminates the employee for engaging in protected activity. For example, an employee filing a complaint to the employer regarding any sexual harassment, discrimination, or participation in unlawful acts by the employer. In addition, an employee refusing to participate in unlawful acts is protected. If the employee is terminated afterward, and on that basis, then that employer has most likely violated the law.
The third exception involves union members. If you are a union member, you may have additional rights beyond those of an at-will employee depending on the strength and bargaining power of your union.
Occasionally, an implied contract to terminate an employee only for good cause can be created through the employer's words or conduct. It has to be reasonable, though, for an employee to conclude that the employer will only terminate that employee with good cause. Some factors in deciding whether an implied contract has been formed are length of employment, raises, promotions, actions or communications on the part of the employer, and practices and policies of both the employer and the industry.
To pursue a successful claim for wrongful termination, the strength of your case depends on the evidence. Documents, emails, texts and witness testimony is essential. If you feel you may have been wrongfully terminated, evidence gathering and critical case evaluation and assessment is critical. The earlier the better.