This could be more serious than you know. With a law like that here in Ore, I could not own a firearm. I have clinical depression which is a mental illness. Every ten or twelve years I have to go on special drugs to straighten out. I have other ways, all legal, of dealing with it in the meantime. I would bet that a good percentage of the people on this site also suffer from it, weather they know it or not or will even admit it. It's very controllable but the stigma attached to "mental illness" keeps many from talking of it or even dealing with it. In truth, it's little worse than a common cold and much more treatable when the person afflicted with it shrugs off the bonds of the stigma.
One of my best friends spent two tours in Vietnam as a field medic. He has PTSD and clinical depression. He hunts and shoots and he's no danger to anyone. When I was training dogs, I had a couple clients with bi-polar disorder. They took their medicine and you could not tell. It's the stigma attached to mental illness that causes more problems than anything and leads to many people not getting a handle on it. In truth it is no different than many illnesses that require the taking of drugs to control it, ie: diabetes, which I also have, high blood pressure ect.
Where the problem comes in is they pass a law stating mental illness and all of a sudden every form of mental illness gets lumped into the law. That would be a bad law as many people that are no danger to anyone would be lumped into the description.