In four states, including Idaho, there is no insanity defense at all. That… (Andrew Harrer / Bloomberg )
As Americans speculate about why a young man in Colorado allegedly engaged in a nightmarish shooting rampage in a movie theater, lawyers for a convicted killer in Idaho are asking the Supreme Court to rule that states must allow defendants to plead not guilty by reason of insanity. The court should do so.
James Holmes, the 24-year-old former graduate student accused of killing 12 people and injuring 58 during a midnight showing of "The Dark Knight Rises," could face the death penalty if convicted. But, like defendants in 46 states, Holmes will be able to plead insanity. In Colorado, a defendant is legally insane if he is "so diseased or defective in mind at the time of the commission of the act as to be incapable of distinguishing right from wrong."
An insanity defense is rarely asserted, and the definition of legal insanity varies from state to state. Half the states, including California, employ a variation of the M'Naghten Rule adopted by the British House of Lords in an 1843 murder case: A defendant is insane if at the time of the crime he either didn't know that what he was doing was wrong or was unable to understand the nature and quality of his act. Other states use a broader definition that defines insanity as the inability of a defendant, because of mental illness, "to conform his conduct to the requirements of the law."
If a defendant is acquitted by reason of insanity, he is not released but committed to a mental institution, sometimes for a period of time longer than the imprisonment he would have received if found guilty. John W. Hinckley Jr. was acquitted in the attempted assassination of President Reagan, but he was sent to a mental hospital after his trial in 1982. Not until 1999 was he permitted supervised trips outside the hospital grounds.
The Hinckley verdict inspired a national outcry. Congress and several states moved to narrow the insanity defense or shift the burden of proof on the question of sanity from the government to the defense, which undermines the principle that the prosecution must establish its case beyond a reasonable doubt. Some states adopted the alternative of a "guilty but mentally ill" verdict, which has popular appeal but is logically contradictory because guilt traditionally has been equated in our legal system with responsibility. In four states, including Idaho, there is no insanity defense at all.
That could change if the Supreme Court agrees to consider an appeal by John Joseph Delling, who argues that some sort of insanity defense is required by the Constitution's guarantee of due process of law. We agree. Not every violent crime is the result of mental illness, but a jury should have the option — after hearing expert testimony from both sides — of deciding that a defendant is legally blameless, even if he must be confined for the protection of others.