Gun control, mental health and trauma

Ever since Sandy Hook, there has been a lot of discussion on the web about gun-control and whether or not it could have saved those children.

My personal belief was that regardless of what caused his mental illness, Adam Lanza was a dangerously unstable young man. His mother should not have been allowed to keep multiple fire-arms within his reach. Would lack of easy access to firearms have stopped him? Not necessarily, but it might have slowed him down and forced him to think twice.

I am told that to check mental health records and interview friends and neighbours of people who share the home of the applicant, or even the applicant himself, is to convict someone before a crime has been committed. In America one is innocent until proven guilty, and one should not be treated as a potential criminal until a crime has been committed. One should not be required to give up one's constitutional rights until there has been a conviction.

It is a noble argument, but I'd like to call bullshit.