As early as the 13th century, it was felt that insane defendants should not be blamed for the consequences of their acts. The basic outline of the insanity defense excludes from the ranks of criminals all persons who are mentally diseased and who cannot reasonably be used to serve the purposes of the criminal law. The purposes of the criminal law seem to change from time to time, however. At first, its purposes were primarily retributive in nature. Then retribution was put aside in favor of deterrence. Lately the trend has been a shift from deterrence to rehabilitation. As the functions of the criminal law changed, so did the insanity defense. Today, in fact, it has become almost no defense at all.
An acquittal in most instances brings no freedom, because the defendant is usually committed to a mental hospital. The purpose of the commitment is to determine whether he