Sounds like you're saying the letter should be required.
No, what I'm saying is, there is no way to effectively implement a requirement to evaluate existing medical records for determining the risk of allowing an individual to own a firearm. Sure, you might find a few who have real problems, but there is no way to know if you are actually preventing anything at all from happening. In fact, few criminals with mental illness commit crimes due to the symptoms of the illness itself. We hear of Son of Sam taking orders from the neighbor's dog, and we think that's how all crazy people think. Not true.
Of the known mentally ill patients of the country, what percentage actually hurts others based on the illness?
In a study of crimes committed by people with serious mental disorders, only 7.5 percent were directly related to symptoms
of mental illness, according to new research published by the American Psychological Association.
Researchers analyzed 429 crimes committed by 143 offenders with three major types of mental illness and found that 3
percent of their crimes were directly related to symptoms of major depression, 4 percent to symptoms of schizophrenia
disorders and 10 percent to symptoms of bipolar disorder.
“When we hear about crimes committed by people with mental illness, they tend to be big headline-making crimes so
they get stuck in people’s heads,” said lead researcher Jillian Peterson, PhD. “The vast majority of people with mental
illness are not violent, not criminal and not dangerous.”
So, the percentage of gun buyers who might have mental illness is small. Of that, the number who commit crimes due to their illness is small.
Trying to use any records-keeping system, including a "letter" saying you are not crazy, is not going to prevent anything.
As we all know, if someone is thinking of ever buying a gun, knowing that their seeking treatment could deny them, they may opt to avoid treatment. Therefore, no record exists even though the person may have been helped had he sought treatment.
Also, people with mental illness do not always go through the background check process. They can do like Sandy Hook's killer and steal from a family member, or they can do like the San Bernardino killers who got their rifles second hand from a friend. Another study shows the majority of career criminals get their guns from friends and known acquaintances, just like San Bernardino. If someone needs a gun, they will find a way without going through the background check.
As with all gun control laws, those most affected by them are the law abiding. Those who are breaking laws like murder could not care less about gun laws. Systems like this that attempt to identify people with certain "flags" in their records would be fine if the denial for gun purchasing was simply on hold until a real clearance evaluation is performed, not just a records check. Of course, that would hinge on the honesty of the patient before an accurate determination is possible.
If we want to get serious about keeping guns away from the mentally ill, then full mental health check-ups need to be performed throughout the patient's life, so there is a baseline with which to compare subsequent evaluations. Mental health issues are best spotted based on behavioral changes such as increased alcohol use, illegal drug use, increased or escalated domestic arguments, drop in school grades or job performance, petty criminal charges like shoplifting, ... anything that demonstrates a change in attitude or caring what happens to them.
Good luck getting anyone to agree to pay for this kind of ongoing evaluation process!
A bad solution cannot be made better by adding more layers of documentation or reviews of existing records. A letter might give the
appearance you've been evaluated properly, but it's a lie if the letter writer has only your records to go on.