"At-will employment doesn't provide a blanket exemption from wrongful termination suits" Well, yeah. Stipulations include forcing someone to do anything illega

"At-will employment doesn't provide a blanket exemption from wrongful termination suits" Well, yeah. Stipulations include forcing someone to do anything illegal, firing someone because they're involved in union activity, or terminating someone based on discrimination. Please CITE a source or a case that concludes you can't fire someone for getting involved in the aforementioned mess in the link above whether he is guilty or not guilty. Thank you.