Good point. I fear gun laws that use the existance of even an expired restraining order as a basis for denying ownership. It's too easy for a vengeful ex to get one based on absolutely no merit.
How about the idea of allowing the accused to challenge the diagnosis in court, with damages allowed for unreasonable defamation? Surely, a truly mentally defective person might not even contest the issue, and if they did, a court might make its own independent findings.
Yikes! You're asking: "How about letting the courts get involved with medical diagnoses?" PLEASE keep the government OUT of medical diagnoses!
Once again, it's the lawyers (and those who file ridiculously and those who award ridiculously) who have trashed our lives pretty badly. Physicians are scared to use their best judgment because of the fear of a lawsuit. They often find that they must err on the side of "caution," in case one of their patients does go off the deep end. And it has gotten to the point where few Americans are even going into psychiatry anymore--it's just not worth it. So we have MANY non-native psychiatrists to fill the gap.
Now, if these were pathologists, peering at microscope slides, then fine. But mental illness is culturally defined (e.g., a shaman might be "visionary" or "schizophrenic," depending on where he is), and do you think that a non-native psychiatrist is going to understand the cultural aspects of a patient's condition as well as an American, even if he's just as good medically?
We've really messed up things badly, but the answer isn't to get the government involved even more, IMHO.