Federal law generally prohibits the possession or acquisition of a firearm by a person "who has been adjudicated as a mental defective or who has been committed to a mental institution." Putting aside the offensive label and legal jargon, in simple terms this means that a person is prohibited for life from possessing firearms if the person has ever been: involuntarily committed to a mental institution, or found by a court to be a danger to himself or others, found not guilty of a crime by reason of insanity or incompetent to stand trial, or unable to manage his own affairs.
It does not matter whether the person currently has a mental illness.
Federal law is both under- and over-inclusive. It is under-inclusive because plenty of people with severe mental illnesses escape the ban on possessing firearms—provided, for example, they have managed not to be formally committed to a mental institution, or found by a court to be incompetent or insane. The ban is over-inclusive because many people recover from mental illness and lead healthy and productive lives.
A single involuntary commitment for a severe eating disorder at age 20 will preclude a person from possessing a hunting rifle for the rest of his life. [...]
Gun-rights advocates should support efforts to strengthen the prohibition on possessing firearms by those who have mental illness. Many people with severe mental illness are too dangerous to entrust with firearms—regardless of whether they have been formally labeled under the current law as ineligible. [...]
As for gun-control advocates, they should show more flexibility about restoring firearm rights for people who may have suffered from mental illness in the past but are no longer a danger. Instead of lobbying to expand the number of people permanently ineligible to possess any type of firearm, gun-control advocates should accept a risk-based approach. [...]
Wall Street Journal Editorial