if you are fired from a job what information can your previous employer disclose to prospective future employers?

Typically, most companies have a policy that they will only provide neutral information, meaning dates of employment and job title.  This is not a law, however.  Rather, the companies typically have this policy to avoid being sued by the former employee for defamation.  Nevertheless, by law, the company can state whatever information is truthful and accurate.  So, if you were terminated for alleged performance issues, the company could state that, as long as they can ultimately prove that this information is accurate should they be sued.