Thirdly, it is important to note that the defense need only prove that the defendant was either unable to “conform” to societal standards, or that he or she was unable to “appreciate the wrongfulness of his or her actions.” One or the other is sufficient to raise the issue of insanity.
The wording of the section in the United States Code that governs the issue of the insanity defense is very specific on this:
First, that the insanity defense “is an affirmative defense to a prosecution under any Federal statute that, at the time of the commission of the acts constituting the offense, the defendant, as a result of a severe mental disease or defect, was unable to appreciate the nature and quality or the wrongfulness of his acts. Mental disease or defect does not otherwise constitute a defense.”
Secondly, “The defendant has the burden of proving the defense of insanity by clear and convincing evidence.”
Chin emphasizes this point. “Just being severely mentally ill in no way means that the insanity defense is available.”
“You have to be unable to appreciate the nature and quality of the wrongfulness of your act,” Chin said. For instance, he said, if “you think you are in a video game,” or, the classic example he said, is that “you think you’re squeezing lemons when really you’re strangling somebody.”
There is rarely need to prove the facts of such a case. As in the Loughner case, where there are eyewitnesses to the shooting and in which he was tackled to the ground while trying to reload his gun, “what happened is never really at issue,” said Delahunt. “It’s a question of why it happened.”
The government, on its end, will try to prove that Loughner can be held responsible for his actions by illustrating that his actions were premeditated and planned, or that the person had the “ability to conform” and at least put on a show of a normal life. They will look, Delahunt said, at “every step of his day” leading up to the shooting: “where he parked…how he concealed the gun as he walked from the car to the place where he fired from,” the fact that he was “using a high capacity clip” as opposed to an ordinary one, that he was “changing clips when they tackled him — that all shows functionality, that all shows understanding of how firearms work.” Any form of planning like that “shows preparation,” Delahunt said. The fact that he hid the gun suggests an “ability to conform.”
“I’d do a time line back in time as far as you can go,” Delahunt says. “Was he taking classes? Working a job? Keeping medical appointments?” he asked, continuing, “Did he do anything like that that a normal person is capable of doing?”
All of which, Delahunt said, would suggest that he had the capacity to live something resembling “a normal life” and to conform.