In a criminal case, competency represents the capacity of a defendant to engage meaningfully and make decisions during the criminal justice process. Mental competency refers to the ability of a person to make rational decisions and express themselves. Thus, if an individual is considered mentally incompetent, they have psychological and psychiatric justifications that are being offered in court as a defense. For example, in the state of Louisiana, the defense of insanity relies on the findings of the M’Naghten Rule. Under the test, a court makes conclusions regarding the evaluation of the defendant in terms of their ability to distinguish between right and wrong at the time when the crime under question was allegedly committed. The party of the defendant bears the burden of proof in such an instance.
When applying the M’Naghten Test, all defendants are presumed to be sane unless they can prove that at the time of committing the criminal act, their state of mind is altered. As a result, they either did not know what they were doing when committing the said act, or they knew but did not know that it was wrong. It is essential to understand the procedural and substantive facets of defense because the insanity issue in some cases remains contestable, such as in United States v. Hinkley, in which the defendant, John Hinkley Jr., was found not guilty by reason of insanity in the attempted assassination of President Ronald Reagan (Philips, 1983).
Besides, even in cases when psychiatric experts agree on a diagnosis, the interpretation of evidence by courts can vary significantly, as seen in R v. Parks and R v. Burgess (Samuels et al., 2007). To conclude, mental competency represents a significant challenge both to the defense and prosecution sides due to the variability of evidence interpretation as well as the impact of other circumstances framing each case.
References
Philips, H. J. Jr. (1983). The insanity defense: Should Louisiana change the rules? Louisiana Law Review, 44(1). Web.
Samuels, A., O’Driscoll, C., & Allnutt, S. (2007). When killing isn’t murder: Psychiatric and psychological defences to murder when the insanity defence is not applicable. Australasian Psychiatry, 15(6). Web.