Insanity defense is one of the ways used by defendants during criminal cases. The approach is one of the oldest defense approaches but is not commonly used in the United States. Insanity defense refers to an affirmative defense in criminal cases whereby the defendant argues that he or she cannot be held liable for their crimes due to mental/psychiatric problems during the time of the act. In this regard, the defendant must prove elements of mental problems for them to convince the jury.
Insanity defense is classified into four different categories. First, irresistible impulse is a defense in which the defendant argues that they cannot be held liable for their actions due to inability to control their emotions/impulses (Brown, 2018). Another defense is the Durham rule, a rule by which the defendant is deemed not guilty for their actions due to a mental illness/defect (Brown, 2018). The M’Naghten Rule supports every defendant who is assumed to be unaware of right or wrong due to a defect of reason when committing a crime (Brown, 2018). Lastly, the model panel code is whereby the defendant is argued to have a diagnosed mental disorder and cannot understand the criminal nature of his/her actions. The most common insanity defense applied by the States is the M’Naghten Rule. However, it is also rarely used as only about 1% of criminal cases in the States apply insanity defense and the success rate of this defense is considered to be less than 25% (Simon, 2018).
The process of assessing the defendant’s insanity begins with a psychiatrist determining whether he or she has adequate training, skills, and knowledge. Then, specialist reviews the relevant information and records related to the defendant’s mental history. The psychiatrist will interview and conduct analyzes on the defendant to obtain the nature of their mental fitness before and during the time of the crime. Further, he or she will provide the findings to the court to be used during the criminal case. A psychologist can be used as an expert witness during an insanity defense since he or she is given the responsibility to provide light on the psychiatric science and clinical knowledge in a given criminal case involving insanity defense (Meynen, 2016). In this regard, as an expert witness, the psychologist’s role is to educate and clarify to the court on psychiatric issues related to the case.
In conclusion, insanity defense refers to cases when the defendants aim to prove mental problems during the time of the crime. The approach also involves the use of a psychologist to provide evidence of either presence or absence of mental problems during a crime. Although the approach was common in the U.S., its use has gone down over the years due to low success rate. Therefore, it is the duty of the defendant to prove beyond reasonable doubt on presence of mental problems during the time of the crime.