While most employment is "at will," which means an employee may be fired at any time and for any reason or for no reason at all, there are some important exceptions. You may be able to prove wrongful termination if you have experienced:
Broken written promises, like contracts
Broken implied promises, including length of employment, history of promotions and positive reviews, and verbal promises of employment
Discrimination
Breaches of good faith
Violations of public policy, including denying time off for jury or military duty, withholding commissions or PTO pay
Retaliation
Fraud
Defamation
Whistle-blowing violations