Today, Jared Loughner, the man who murdered six people and wounded others (including former Rep. Gabby Giffords) in Tucson last year, will plead guilty. In return, he will be spared the death penalty. Loughner is clearly mentally ill, so how can he plead guilty? To understand, we need to know two concepts: competency and insanity.
Competency to stand trial asks whether the defendant is now mentally capable of understanding the charges against him and assisting in his own defense. It is about mental state now — at the time of trial. It does not reference the defendant’s mental state at the time of the crime.
The insanity defense differs from state to state. The basic idea is whether, at the time of the crime, the defendant suffered from a mental disease that either 1) kept the defendant from understanding that his or her act was wrong (e.g., thought he was shooting a pumpkin, not a person, due to delusions), or 2) kept him from controlling his actions (e.g., because of command hallucinations). Many jurisdictions have narrowed this definition, 1) by saying that it only includes mental disease that keeps the defendant from knowing that the act was wrong and does not include an inability to control his actions, 2) by stipulating that the mental disease must be especially severe, or 3) by abolishing the insanity defense altogether (four states have done this).
The are two big differences. First, competency is about the defendant’s mental state now — when the trial is to take place; insanity is about the defendant’s mental state when the crime occurred. Imagine a person who might have been very ill at the time of the crime, but who, through medication before trial, is well enough to understand his case at trial. Second, the mental illness standard to be competent is very low, but for an insanity defense it is very high. To be competent, one need only be mentally stable enough to understand the charges and talk to one’s lawyer about them; for insanity, the defendant must have been so ill that he or she had no idea her act was wrong.
There are many nuances, but those are the basics. Loughner, after medication in prison, is apparently well enough to be competent, but might still put on an insanity defense about his mental state at the time of the crime. Thus we have the plea deal, which keeps the state from having to put on a trial which would be painful for the victims, and which avoids the risk of the death penalty for Loughner.