If you have a union to advocate your rights or if you negotiated an employment contract you have protection. Otherwise, an employee at will has little or no recourse. An at will employee can be fired for any reason, a bad reason or no reason at all.
Discrimination based on age, gender, race, religious belief, disability etc.... might provide a different answer.
See my Legal Guide "Workplace Discrimination: A Basis for Wrongful Termination Claims" which you might find helpful.
You might find my Legal Guide helpful "How to Choose A Lawyer For You"
You might find my Legal Guide helpful " What Do I Tell My Lawyer"
Check with a lawyer in your locale to discuss more of the details if you have a retaliation discrimination theory.
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