We all agree, and probably this is almost universal, that seriously mentally ill people should not be permitted to purchase a firearm.
First of all mental illness is a medical problem not a criminal one. There are no criminal laws against simply having a mental illness. Involuntary commitments are usually a civil court issue. In fact the only time I can think of when a criminal court can order a mental health evaluation,
not treatment, is determining if a defendant who has been charged with committing a crime is competent to stand trial. There is debate whether the accused/patient can be forcably medicated so he can stand trial.
The Substance Abuse and Mental Health Services Administrative (SAMHSA) released a report recently on mental health statistics for our country. They found that in the past year, 45.9 million Americans above the age of 18 years, or 20% of American adults, experienced mental illness. The Center for Disease Control agrees with those statistics.
http://www.treatmentsolutions.com/mental-illness-statistics/
With a adult population as of September 7, 2012, is approximately 314,325,838. So 20% of that number is 62,865,167.
Second; this part of the report is very interesting;
“Mental illness is not an isolated public health problem. Cardiovascular disease, diabetes, and obesity often co-exist with mental illness and treatment of the mental illness can reduce the effects of these disorders.”
So now medical evidence supports that people who have heart disease, diabetes and are overweight directly contributes to mental illness.
The CDC estimates that every year 935,000 Americans have a heart attack
http://www.cdc.gov/HeartDisease/facts.htm
The American Diabetes Association estimates that 25.8 million children and adults in the United States—8.3% of the population—have diabetes.
http://www.diabetes.org/diabetes-basics/diabetes-statistics/
Our friends at the CDC estimates that the percent of adults age 20 years and over who are obese: 35.9%
http://www.cdc.gov/nchs/fastats/overwt.htm
Third is the pesky 5th, 6th, 7th and 8th Amendments of the Bill of Rights getting in the way again.
If mental illness is to be judged as a crime instead of medical issue then we have;
Fifth Amendment - Rights of Persons
No person shall be held to answer for a capital, or otherwise infamous crime, unless on a presentment or indictment of a Grand Jury, except in cases arising in the land or naval forces, or in the Militia, when in actual service in time of War or public danger;
nor shall any person be subject for the same offence to be twice put in jeopardy of life or limb; nor shall be compelled in any criminal case to be a witness against himself, nor be deprived of life, liberty, or property, without due process of law; nor shall private property be taken for public use, without just compensation.
Sixth Amendment - Rights of Accused in Criminal Prosecutions
In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the State and district wherein the crime shall have been committed, which district shall have been previously ascertained by law, and
to be informed of the nature and cause of the accusation; to be confronted with the witnesses against him; to have compulsory process for obtaining witnesses in his favor, and to have the Assistance of Counsel for his defence.
On the other hand if it is to be tried as a civil case then we have;
Seventh Amendment - Civil Trials
In Suits at common law, where the value in controversy shall exceed twenty dollars,
the right of trial by jury shall be preserved, and no fact tried by a jury, shall be otherwise re-examined in any Court of the United States, than according to the rules of the common law.
And what about posting bail?
Eighth Amendment - Further Guarantees in Criminal Cases
Excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted.
Is someone who is accused of being "mentally ill" going to be denied bail before trial. If so why even have a trial?
Once you let the nose of the camel under the tent...well you get the point.