Two federal court filings Monday in the criminal case of the man accused in the January shooting of Rep. Gabrielle Giffords and 18 others in Tucson, Ariz., strongly suggest that two health professionals who evaluated his mental state have determined he isn’t competent to stand trial, according to legal experts.

☛ The Wall Street Journal: “by John R. Emshwiller and Tamara Audi, May 17, 2011

If he’s mentally ill (a clinical term) does that mean he cannot be held accountable for his actions? Isn’t this precisely the kind of case where the defense could plead “not guilty by reason of insanity”?
Not in this case. Interestingly enough, the explanation has to do with John Hinckley Jr.’s failed assassination attempt against President Ronald Reagan in 1984. At his trial, Hinckley was found not guilty by reason of insanity and was confined at a psychiatric hospital in Washington, D.C.
The verdict was not well received by the general public. As a result, a number of states modified the law while three states abolished it altogether.
In the Wall Street Journal article quoted above, one can read:

In cases where a defendant is found incompetent to stand trial, the defendant is kept in custody until it is determined he is able to understand the charges against him and able to aid his lawyers in his own defense. Such people could be treated with drugs, possibly without their consent, legal experts said.

This is because Arizona is one of the states that modified the law after Hinckley’s trial. Here’s how an article from The Associated Press found at Law.com explains it:

Arizona also has modified the insanity defense so that a defendant in a state trial no longer can be found not guilty by reason of insanity. Instead, the jury can deliver a verdict of guilty but insane, said Pima County Attorney Barbara LaWall. “So the person is held at a state mental hospital, and if sanity somehow comes back, he’s transferred to prison, not just let go,” LaWall said.
The case against Loughner is at an early stage, as is his defense.
His lawyers probably will spend their time making the strongest possible argument to dissuade prosecutors from pursuing the death penalty. “That’s the task of his lawyer in the first instance,” said Neal Sonnett, a Miami defense lawyer.
Among arguments that could be made is that, if not insane, Loughner was mentally impaired. That argument concedes that a defendant bears some responsibility for what he has done but lacks the guilt necessary to face the death penalty. The compromised state of mind sometimes is referred to as “diminished capacity.”
Dershowitz predicted that federal officials will seek death for Loughner no matter what his lawyers argue. “The prosecution will seek the maximum punishment in a case like this,” he said. (Law.com: “Insanity Defense Could Be Difficult for Ariz. Shooting Suspect” by Mark Sherman, January 11, 2011

Previously on Aphelis: “Insanity” as a legal term in the United-States (Jan 28, 2011)