Joan Rivers: Melissa Sues Clinic Over Mom's Death

Melissa Rivers has just filed a huge lawsuit against the clinic where Joan Rivers' heart stopped beating ... and Melissa's lawyer says the doctors acted like a bunch of groupies and not medical professionals.

The lawsuit -- obtained by TMZ -- claims gross medical malpractice, alleging during the 20 minutes doctors tried to bring Joan back to life, they didn't think to perform a tracheotomy, which facilitates breathing.