. . .
In the USA, in most places, owning a handgun/shotgun/rifle is legal provided one is not a convicted felon, mentally incompetent, on psychiatric medicines, or under a certain age. Most states require background checks to verify the aforementioned things.
However, those states allow a person who was *voluntarily* committed to a psychiatric facility to purchase a gun correct? I can't recall, but it seems this was an issue with one of the rampaging workplace shootings recently.