MPC Standard

The Case: United States v. Brawner

Archie W. Brawner was convicted of second degree murder and carrying a dangerous weapon. Upon appealing the case, the standard of Durham was called into question. From the Court Opinions: ‘A difficulty arose under the Durham rule in application. The rule was devised to facilitate the giving of testimony by medical experts in the context of a legal rule, with the jury called upon to reach a composite conclusion that had medical, legal and moral components.’.  It was also stated that simply having a mental disease or defect is not enough to remove a person’s responsibility for a crime. The court held that there must be a relationship between the disease and the act, and that relationship must justify a ‘reasonable inference’ that that action would not have been taken by a person not suffering from the disease.

The Rule

The strict M’Naghten Rules and the lenient Durham standard were superseded by the Model Penal code in 1962 (sometimes called the American Law Institute standard).  It aimed for a balance between the two. It stipulated that “if at the time of such conduct as a result of mental disease or defect he lacks substantial capacity either to appreciate the criminality of his conduct or to conform his conduct to the requirements of the law.” the defendant would not be responsible for criminal conduct. In this it approaches both the ability to understand a crime as well as the willingness to act. This allowed for both the understanding (or lack thereof) of right and wrong, as well as the will to act. Coherent thought and competency were also addressed. At this point the burden of proof rested on the prosecution.

Insanity Defense Reform Act

It is impossible to discuss the MPC without also mentioning The Insanity Defense Reform Act of 1984. This occurred in direct response to the public outcry regarding the ‘not guilty by reason of insanity’ verdict John Hinckley Jr. received after his attempted assassination of President Ronald Reagan.

The Case

On March 30, 1981 John Hinckley attempted to assassinate President Ronald Reagan, wounding four people in the process. At his trial, Hinckley argued that he suffered from a mental disease and that his behavior was a product of that disease. On June 21, 1982 he was found Not Guilty by reason of insanity and committed to St. Elizabeths Hospital.

The implications of the attack and subsequent trial upset much of the public and caused a massive response. This is a good example of the interactive relationship between law, social consciousness, and psychology. The public backlash was so great that

In this act the burden of proof was shifted from the prosecution to the defense, meaning that for an insanity defense to be successful, the defendant must be proven to have been insane at the time of the crime rather than having the prosecution simply fail to prove his sanity. The standard of evidence was changed from ‘preponderance of evidence’ (a balance of probabilities, showing insanity was more likely than not) to ‘clear and convincing evidence’, a higher burden of proof than before.


Twelve states created a ‘Guilty But Mentally Ill’ verdict, which resulted in a criminal conviction and sentance. The defendant is evaluated to determine if psychiatric treatment is required. If it is deemed necessary, the defandant is hospitalized and, once no longer deemed mentally in need of treatment, is placed back in prison to serve the remaining sentence

A more in-depth examination of the affects of the Hinckley trial can be found at:


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