Sounds to me like you violated the policy, tried to cover it up, and were rightfully fired.
The author is a Maryland attorney; however no answer given on Avvo is intended as legal advice or intended to create an attorney-client relationship. Dan's expertise lies in the electronic entertainment (video game) industry, as well as complex internet law issues, electronic free speech, entertainment law, copyright and trademark law, and computer fraud. He primarily represents game developers and founders of emergent internet technologies.
Unless you had a written employment contract, you were an at will employee, which means you could be fired for any reason, as long as it did not involve discrimination on grounds of race, sex, sexual orientation, religion, age, etc. Violation of a social networking policy in this matter is a serious transgression for a company manager---it certainly could form the basis for termination.
Was there some specific reason that you posted this info? You knew about the policy. What facts and circumstances explain this lapse by you? In the absence of some very compelling explanation, you very likely were not only lawfully terminated but you will likely be without UI benefits.
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