While employment at will is the law in most states, there are a number of exceptions to this general rule that have been created both by statute and by the courts. Through these exceptions, and contrary to an almost common belief, employers cannot necessarily terminate employees for any reason.
Federal antidiscrimination laws protect employees from losing their jobs on the basis of their race, color, national origin, sex, religion, disability, pregnancy, age, or genetic information. Employees can sue their former employers under a variety of antidiscrimination laws, including Title VII of the Civil Rights Act of 1964 (42 USC Sec. 2000e et seq.), the Americans with Disabilities Act (ADA) (42 USC Sec. 12101 et seq.), the Pregnancy Discrimination Act (PDA), the Equal Pay Act(29 USC Sec. 206d), the Age Discrimination in Employment Act (ADEA) (29 USC Sec. 621 et seq.), and the Genetic Information Nondiscrimination Act (GINA) (42 USC Sec. 2000ff).
In addition, most states have enacted their own laws prohibiting discrimination in employment, some of which include additional protected classes such as sexual orientation, marital status, and military membership.