Over on Peter Earley's blog there is a post entitled "How Fair Is The Insanity Defense" that you should all go over and read. I thought about writing a comment there but quickly released this would require a post of its own, so here it is.
He starts out with a case description of a man with an undoubtedly severe mental illness who either shot or assaulted many people while delusional. In 1992, after a failed attempt at civil commitment, he shot and killed two people. At trial state psychiatrists testified that he knew killing was wrong, even though motivated by delusion---in other words, a legally sane crime by the McNaughten test of insanity (which Mr. Earley describes well, I won't be repetitive here). He was sentenced to death and eventually executed in spite of a recommendation for commutation by the Texas Board of Pardon and Paroles.
Mr. Earley is critical of the McNaughten test and feels that we should rethink the legal definition of insanity. He also advocates to end the use of private forensic experts, a point I'll return to later.
First, I think the public should understand there is a certain logic to when and how a defense attorney decides to file an insanity plea. Mr. Earley is appropriately critical of attorneys who file the plea "when their client is obviously guilty and they don't have any other rational explanation to fall back on." It's true that there is sometimes a hidden agenda for requesting a sanity evaluation: there may be a chance that an evaluation could turn up mitigating information that could be used at sentencing, or as leverage in a plea bargain.
Setting aside the hidden agenda, the fact of the matter is that insanity pleas are filed rarely compared to the overall number of offenses that happen every year. This is particularly true of misdemeanors. That's because an insanity plea, if successful, could lead to the defendant ending up under court or health and mental hygiene supervision for years. A simple guilty plea could get a client out of jail, with or without supervision, in months. The attorney is obligated to act in the stated wishes of his client, and that wish is obviously going to be to get out as soon as possible. Thus, we usually only see insanity pleas filed in very serious, felony cases.
So how rare is it? In Maryland, an insanity plea is filed in fewer than one-half of one percent of all crimes commited in a year, both in Circuit and District Court. Out of all crimes committed in Maryland, only 0.032% end in a successful insanity verdict. This certainly doesn't suggest that the defense is being abused.
Regarding the proposal to use court appointed experts (please see also my previous post on private evaluations):
We're already doing that. Most jurisdictions have individual psychiatrists or psychologists working on behalf of the court, either in a court-affiliated medical clinic or under contract with the state's department of health. As the system usually works, this independent court-appointed evaluator completes an assessment and sends a report with an opinion about sanity back to the judge who ordered the evaluation, with a copy sent to the defense attorney who filed the plea and to the prosecution. (Exact details of who gets the report, when they get it and how it can be used may vary between states. I'm speaking in very general terms here.)
Then and only then will a private expert get involved, mainly because one side or the other won't be happy with the independent expert's opinion. In my experience, this usually takes place when the independent expert thinks a defendant is sane and the defense wants to challenge the report. In Maryland, if the court's expert finds someone insane that opinion is almost never challenged by the prosecution because both sides recognize, and agree, that this person is very very sick. (I think the number is somewhere near 90% agreement on insanity but I don't have the study in front of me.)
In short, the insanity defense is hardly ever used and private forensic expert involvement is even less common than that. Out of a few hundred evaluations done every year in our forensic hospital, only a handful will involve a private opposing expert.
Whether or not the legal test of insanity should be changed is an issue that arises regularly throughout history, most recently in 1984 following the assassination attempt on Ronald Reagan. Then, Congress passed the Insanity Defense Reform Act which changed the test on a Federal level. It excluded any category of mental illness from serving as the basis of an insanity plea unless the diagnosis was a "serious" mental illness. Many states, including Maryland, revised their insanity statutes following the Hinckley verdict. Four states have completely abolished the insanity defense.
And I guess that's the trick when it comes to opening the bag of worms of insanity reform: there's always the chance, particularly given the outrage following the Connecticut shooting, that the defense could be thrown out altogether. And then where would my seriously mentally ill forensic patients be? The Supreme Court recently had the opportunity to hear a case that would have challenged the constitutionality of a state statute barring the defense, but they turned the case down.
OK, that's wraps up my response. I just wanted to provide a little more background and factual information to the topic since it is going to be discussed a lot in the news as certain high profile cases come to trial.