Can an employer ask a therapist about an employee's mental stability and does this go against the HIPAA?

If you are the therapist in question, you should ask your licensing authority this question, or look it up in your code of ethical conduct. I do not know the answer If you are not the therapist , I still do not know the answer, but I suspect the employer should ask, if they have concerns about danger to him/herself or others in the work place. I also suspect the therapist is required to divulge such information to some one.

The employer can ask; it is the duty of the therapist to keep the information confidential. However, if you signed a release, either when therapy started or as part of the employer paying for your health care, then the therapist would be allowed to tell the employer. Also, talk with your therapist. I believe that the confidentiality requirement may not apply if you are a danger to yourself or others.

In some instances, an employer can communicate with an employee's health care provider. An attorney would need full and complete information to adequately respond to your concern.

I don't know HIPAA law but I do know employment law. Under employment law, generally, an employer can ask whatever they want, so long as they have no intent to violate civil rights laws or discrimination laws. of course, if it leads to being fired and an employee believes the firing was based on unlawful discrimination, the employee could file a discrimination complaint.