The court’s decision has angered many people, including the former first lady, Nancy Reagan, and James Brady, who was severely wounded in Hinckley’s attack. (Two others were also injured.) Former Reagan aides, such as Patrick Buchanan, have expressed outrage.

Ad hoc outrage, however, is worth little. Unless the crux of the case — the insanity plea and verdict — is addressed, decisions such as this will continue to be made.

Hinckley was found not guilty of shooting the president and the others because he was said to be insane; that is, at the time of the shooting he is supposed to have had a mental illness that prevented him from appreciating the nature of his act. If one accepts such a disposition as a matter of principle, then one has no principled grounds to object when the government’s psychiatrists say his illness is in remission and he is no longer a danger to others. After all, Hinckley was committed to a mental hospital ostensibly for treatment, not punishment. His confinement was contingent on his being ill and, as a result, dangerous. If the experts said he was no longer ill, there would be no further grounds under the law for holding him.

Given the premise — insanity — the conclusion follows. If freeing Hinckley for unsupervised visits is outrageous it is because acquittal by reason of insanity is outrageous. The judge could not have permitted the visits had Hinckley been found guilty of attempted murder and sentenced to life in prison.

What is it about Hinckley’s act that indicated insanity? He says he tried to kill the president of the United States to attract the attention of a movie actress, Jodie Foster. Is there any reason to think that Hinckley, who was 25 at the time, did not really know what he was doing? To ask the question is to answer it. Who can seriously doubt that he understood that firing a bullet into Reagan’s body could kill him? Who can seriously doubt that he knew this was wrong? That he did it for a screwy reason does not diminish his responsibility.

Could he have chosen otherwise? To answer no, one would have to believe that Hinckley had no choice but to purchase a gun, book a flight, board an airplane to Washington, ascertain the whereabouts of President Reagan on March 30, 1981, wait for him to exit the Washington Hilton, and pull the trigger several times. Are we to believe that an illness made him do all this?

Thomas Szasz, the foremost psychiatrist-critic of psychiatry, has been a relentless critic of the insanity defense and verdict for 50 years. He writes, “Regardless of whether a person is deemed sane or insane, a person has reasons, not causes, for his actions. If we reject the actor’s reasons as absurd, crazy, or meaningless, then we consider and call him mentally ill. That, however, hardly constitutes proof that his alleged condition caused him to commit the forbidden act.”

The unsubstantiated claim that the insane suffer from a brain disease cannot salvage the insanity defense. “A brain disease may, indeed be a cause,” Szasz writes. “But a cause of what? Typically, of a functional deficit, such as weakness, blindness, paralysis. No brain disease causes complex, coordinated behaviors, such as the crimes committed by John W. Hinckley, Jr.”

The insanity defense is not about compassion. It’s about escaping responsibility for bad acts. It is the mark of a free society that people are to be left alone so long as they do not injure others, and they are to be accountable for their actions when they do. Thus the insanity defense strikes at the very heart of our most cherished principles.

Sheldon Richman is senior fellow at The Future of Freedom Foundation, author of Tethered Citizens: Time to Repeal the Welfare State, and editor of Ideas on Liberty magazine. Send him email.