The insanity defense is a serious claim which may have various consequences. On the one hand, it protects mentally ill people who cannot bear responsibility due to their psychiatric condition; on the other hand, it may be a way for dangerous criminals to escape justice. Insanity is a criminal term rather than psychological, and terminological ambiguity sometimes gives a way to corruption in courts. In most states, a defendant may plead insanity which will be further tested. According to the statistics, the insanity defense is used in 1 percent of all criminal cases, and a quarter of cases which use this type of defense are successful.
The major problem with insanity defense concerns the person eligible to testify the sanity of the defendant. More than a half of the states require forensic psychiatrists to witness the mental impairment. The prosecution and the defense pay these experts who rely on further certifications or tests. There are three standard procedures for labeling a defendant as insane – M’Naghten, Durham, and ALI tests. According to these tests, defendants who are not guilty by reason of insanity either do not know about the wrong nature of the committed act or cannot control the behavior which results from mental impairment. In courts, forensic psychiatrists usually testify for the both sides of the trial.
As a matter of fact, there are no other people but psychologists to testify about the insanity of defendants irrespective of tests used to prove it. Defense psychologists cannot testify the insanity of the defendant at the moment of crime as it shall be decided due to the forensic evidence. In general, the defense and the prosecution have their own experts. In case the defendant cannot allow the expert to testify on their mental impairment, judges appoint government-paid psychiatrists.