This action by the employer was not wrongful termination. While there are no laws that require confidentiality about promotions, many companies have such a policy in place. Discussing the promotion prematurely (apparently in public) you showed poor judgment that caused your termination.
There may be other reasons for your termination that the employer did not reveal. It is likely that you simply gave the employer a reason to do something he wanted to do anyway. Office politics may lie at the root of this incident and not the promotion. It seems your employee was within his rights but, this is a free country where anyone can sue anyone else. You are free to hire a lawyer and sue your former employer.
Hope that helps you out. =)
A note about HR laws:
Laws concerning employee treatment, benefits, hiring and firingâ€¦etc are multi-level. What this means is that there are Federal laws, state laws and sometimes local regulations that have jurisdiction over an employee. The information presented here should not be considered legal advice. Ultimately, employers with serious legal questions should consult local attorneys with expertise in worker relations.
The questions and answers presented here are based on research and data from internet sources and should not be considered the final word.