What can potential employers ask past employers?

Absolutely anything it wishes to say. Former employers SHOULD stick to facts, but no defamation law requires that.

the polight thing to do would be to ask about their job experience.If they decide to mention why they left,let them.If not,don't force them to tell you,unless they are a close friend

Present employer is allowed to call past employer. However, past employer is not obligated to say anything without a signed waiver from employee ... which is what most employers are doing now to...

Yes, a potential employer can legally ask for your previous salary, and this is standard in business. There are several reasons they ask this questions. 1. It's a good indication as to whether their...

You might get a job offer over the phone.