In some ways it seems so obvious: any person who would plan to assassinate a public official, buy a gun, actually carry out the shooting, and kill people must be insane! Right?

So will Jared Loughner, the shooter in Arizona, get off by reason of insanity in his cases?

Under the law in most states, if a person is insane at the time of the commission of a crime that can be used as a defense. It doesn’t mean the person is innocent. It does mean that if a jury decides the person was insane, they can find him not guilty.

Before we look at Mr. Loughner’s situation, it’s important to understand the insanity defense. For more than 700 years English common law has recognized this defense in criminal proceedings. The case that defined the law occurred in 1843 with a defendant named Daniel McNaughton. Today, the law of the defense of insanity is called the “McNaughton Rule.”

Here in Minnesota we use the McNaughton Rule in criminal cases. Mr. Loughner faces charges in both Arizona state court and federal court. Both of these courts use a restricted form of the McNaughton Rule.

What is the rule?

In Minnesota, the rule has been included in the Rules of Criminal Procedure which says that it’s a defense to a crime “if the accused was laboring under such a defect of reason, as not to know the nature of the act or that it was wrong.”

Here’s how the process generally works in a criminal case:

1. The defense lawyer notifies the court and the prosecutor that the accused will assert the defense of insanity.

2. The court will order a mental health examination of the accused by a trained professional who will advise the court if the defendant “labored under such a defect…” or not. (Professional is usually a psychiatrist)

3. If either side disagrees with the expert’s opinion, they may ask for a second opinion from a different doctor.

4. If either of the experts say the accused was insane, that issue can be presented to the jury through the testimony of the expert at trial.

The jury would make the decision about the ultimate question: is the defendant not guilty by reason of insanity?

Does “it work” very often? Are people often found not guilty by reason of insanity? Not in my over thirty years of experience. The McNaughton Rule is very narrow and difficult to fit within. Over the years, there have been other definitions of insanity tried in the courts which have been broader. Today, we’re back to the McNaughton Rule and very, very few accused people are found not guilty as a result.

Still, it’s a valid defense and there are some cases where it’s obvious to everyone the accused is insane. What if a jury were to acquit someone because of insanity? In my next post, we’ll discuss what happens in that case.

What do you think? Should the definition of insanity be broadened to include more people who are seriously mentally ill?