If you’ve been terminated from your job, you may have grounds for legal recourse if you were terminated for 1) being a part of a protected class or 2) blowing the whistle on your employer’s violation of the law.

Regarding termination for being part of a protected class: Essentially, everything it requires to prevail on a discrimination claim applies to a discrimination based wrongful termination claim. The only difference is now you are bringing suit to prove it was in fact discriminatory motive that provided the basis for your termination. 

So, whatever documentation you have to show that your employer fired you for your race, gender, sexual orientation, religion, or age (over 40) would be critical for winning your case. It is also going to help if you have any documented complaints of the discrimination prior to your termination.