If your HR manager lies about something big, like telling a potential employer why they fired you or even slandering your name due to a grudge, those may be considered libel or slander and could be violations of defamation laws and could lead to legal action.
Can you be honest with HR?
Yes. Its so important be open and honest with HR to ensure your happiness at a company, especially if you dont feel as comfortable speaking with your manager. However, make sure to keep your tone and body language professional. It is important not to deliberately lie to your HR department.
Can you call your boss a liar?
By saying nothing, your silence might indicate you agree with the falsehood. One thing not to do is use vulgar or abusive language as this can jeopardize your unemployment if you get fired. If you are going to point out your disagreement, try to make clear you are not calling your boss a liar.
Can HR tell your boss to fire you?
Yes. Your manager does not have to be the one to fire you. The HR manager at your company can be the one to deliver the bad news. It is up to each company to decide the involvement HR has in the actual verbal firing.