I am a law school graduate currently awaiting Bar results. What I offer is mere information, not to be construed as forming an attorney-client relationship.
Well, you have two issues here:
1) Regarding former employers sharing or revealing your personnel files with others:
they can reveal such information pertinent to your job performance with new or potential employers seeking background info on you when you list such former employer on your application. It implies that the new employer has permission to contact them. The only way former employers can be in trouble for revealing too much or for defamation, is going beyond what was consented by you and saying personal attacks or medical history. In a nutshell, items that go beyond your direct performance as a good/bad employee -- work ethic.
2) Regarding employer sharing medical files with employees -- they cannot do that when it has nothing to do with let's say insurance purposes etc. If they do on a whim for no reason, that is an intrusion of privacy. As a result, both the indivual who revealed the information, as well as the company, may be liable.
I suggest reading the employment labor law main heading and all applicable sub headings at freeadvice.com's home page.
Hope this helps.
