My point is, if you are the seller of a firearm, how do you find out if the buyer has been adjudicated to be mentally deficient if the government/background check cannot look at the health records of the purchaser. I agree not all mental health illness necessarily means you cannot purchase a firearm. The term is to broad. I think we can agree though that there are types of mental health illnesses that should eliminate a person from owning a firearm. How do we allow the owner to be aware of the mental health of a purchaser?
Do you believe that a person with any level of mental health issues, from intellectual disabiliy to schizophrenia should be able to own a firearm? If you don't how do you find out if a person has such mental illness?
Wizard makes some valuable distinctions with the emphasis on due process, which is reserved for those patients who may need involuntary holds or hospitalization - temporary or permanent - due to mental incompetence or danger to themselves or others. The vast majority of people with possible mental health issues enter the health care system with acute changes (e.g. ER) or are seen through their primary physician for their complaints (anxiety, depression, behavior changes).
Much of the initial psych screening relies on self-reporting, e.g. "Have you thought of killing yourself or others?" and cooperation with the
screening tools for assessment. Lengthy assessment questionnaires are best done in a specialist's practice and also require cooperation. Where I live, psych appointments for non-emergent situations may be six months out. All that documentation is privileged and protected.
So, if you have a state law that merely says that handgun sales are prohibited to people with mental illness without any specification, that can be worthless to provide a seller with guidance or put the person in a database unless they have committed a violent crime. With Internet gun sales, the seller does not even have to look the buyer in the eye.
At gun shows, the only criteria is "[a]ny person may sell a firearm to an unlicensed resident of the State where he resides as long as he does not know or have reasonable cause to believe the person is prohibited from receiving or possessing firearms". No waiting period or criminal background check in databases even if those databases included someone who was adjudicated with uncontrolled paranoid schizophrenia with a finding that they are a danger to others with homicidal ideations.