McNaughton Rule, Durham Rule, and the Insanity Defense
This paper traces the historical development of the insanity defense in American and British law, focusing on three major legal standards: the McNaughton Rule, the Durham Rule, and the US Federal Rule. It examines the origins of each standard and analyzes how landmark cases — particularly those involving John Hinckley Jr. and Andrea Yates — shaped public perception and legislative reform. The paper also considers how different states apply the Model Penal Code and discusses the ongoing tension between legal formalism and scientific understanding of mental illness in criminal proceedings.
- Introduction to the Insanity Defense: Origins of the McNaughton Rule and insanity standard
- Major Legal Standards for Insanity: Durham Rule, Federal Rule, and Model Penal Code
- The John Hinckley Jr. Case: Hinckley's assassination attempt and insanity acquittal
- The Andrea Yates Case: Yates postpartum psychosis defense and conviction
- Public Outcry and Legislative Reform: Legislative backlash and insanity defense reforms
✍️ How to write this paper — guide, tools & examples ▾
What makes this paper effective
- It grounds abstract legal standards in concrete, well-known cases, making complex doctrine accessible and memorable.
- It traces a clear historical progression — from McNaughton to Durham to the Federal Rule — showing how each standard emerged as a reaction to the limitations of its predecessor.
- It balances legal analysis with social commentary, noting how high-profile verdicts drove legislative change rather than purely legal reasoning.
Key academic technique demonstrated
The paper uses case study analysis to illustrate doctrinal evolution. Rather than defining legal rules in the abstract, it anchors each standard to a specific historical moment or trial outcome, demonstrating how law develops in response to real-world events. This technique is especially effective in legal studies writing, where doctrine and precedent are best understood through their application.
Structure breakdown
The paper opens by establishing the origins of the McNaughton Rule, then moves chronologically through the Durham Rule and the US Federal Rule. It transitions into two detailed case studies — Hinckley and Yates — before concluding with an analysis of the public and legislative backlash triggered by the Hinckley verdict. Each section builds on the previous one, linking legal standards to real-world consequences.
Introduction to the Insanity Defense
The name McNaughton derives from the son of a Glasgow wood turner who suffered from the delusion that a conspiracy was being organized against him — that Catholic priests had sent spies to harass him. It is from these encounters that the McNaughton Rule came into being. The rule is grounded in understanding the difference between right and wrong. It serves as a test of two concepts: "knowing right and wrong by oneself in the course of their actions" (Asokan, 2007). The idea of uncontrollable impulses was not considered a significant factor. This rule became the standard test applied by juries after hearing medical testimony. As a result, there was a presumption of sanity unless the defense proved otherwise. Both the United States and the United Kingdom adopted the McNaughton Rule, and many states continue to use it to handle cases to this day (The 'insanity defense' and diminished capacity, 2017).
Major Legal Standards for Insanity
The Durham Rule
Durham was a man who had been arrested and convicted several times. He had also been admitted to several mental institutions on multiple occasions since the age of 17. Despite a 1953 ruling against him — to the effect that the defense had failed to prove he did not know what he was doing — the appellate judge thought otherwise. This served as the beginning of the end of the McNaughton Rule. The judge drew on existing research to declare that the McNaughton Rule was obsolete and misleading, pointing out that relevant scientific findings disproved the assumptions embedded in it. The judge overturned the conviction and established a new standard known as the Durham Rule. This rule holds that an accused person is not criminally responsible if the unlawful act was the product of a mental disease or defect (The 'insanity defense' and diminished capacity, 2017).
The US Federal Rule
The Insanity Defense Act in federal courts now requires the defense to demonstrate clearly that the defendant was not in control of their faculties at the time the unlawful act was committed. This approach is viewed by some as retrogressive — a return to the older standard. It was accompanied by the Insanity Defense Reform Act, enacted in 1984, which introduced guidelines for sentencing defendants with a history of mental illness (The 'insanity defense' and diminished capacity, 2017).
The Model Penal Code Rule
New York applies the Model Penal Code Rule. This rule places the burden of proof on the defendant (The Insanity Defense Among the States, 2017). It also grants legislative authorities the freedom to choose between the language of "wrongfulness" and "criminality." As a result, legislative bodies may adopt a more legalistic view of right and wrong, or alternatively apply a morally inspired standard. Complications arise in the evaluation of right and wrong in cases where individuals — despite knowing they would be condemned by society — believe that the same society would view their actions differently if it were aware of what they "knew." Such cases represent classic and problematic scenarios for courts (Francone, 2016).
The McNaughton Rule was adopted in both the United States and the United Kingdom and was applied as the standard of insanity for many years. The rule is still used as the primary insanity test in nearly half of US states. The Durham Rule, by contrast, relied on scientific research to evaluate insanity in court — a departure from the legal formalism of the McNaughton approach. Scientific explanation became the basis for judgment. However, controversy eventually pushed the Durham Rule to the margins. The underlying premise of the Durham Rule was that punishment is intended to deter criminal behavior. If a person cannot distinguish right from wrong, applying the law rigidly serves no purpose (Francone, 2016).
The John Hinckley Jr. Case
Hinckley became obsessed with the 1976 film Taxi Driver, in which Jodie Foster plays a child prostitute and Robert De Niro plays Travis Bickle, a character who plots to assassinate a presidential candidate. Hinckley watched the film repeatedly and developed an intense fixation on the actress. He set out to find Foster by stalking her, eventually relocating to New Haven, Connecticut, and enrolling in a writing class at Yale University, where Foster was a student. He called her persistently and attempted to push notes under her door, at one point threatening to take his own life to attract her attention.
In 1981, Hinckley attempted to assassinate President Ronald Reagan outside a Washington, D.C. hotel. Several people were injured in the shooting. According to reporting at the time, Hinckley later claimed that he acted out of love — describing his feelings for Foster in terms resembling Romeo and Juliet. The defense team entered a plea of insanity. They succeeded: Hinckley was acquitted on all 13 charges and committed to a psychiatric facility. Owing to the enormous publicity surrounding the case, the public came to view the insanity defense as a legal loophole — a mechanism by which a clearly guilty party could evade punishment (Yoong, 2012).
Most US states were subsequently compelled to reform their legislation regarding the application of the insanity defense following the ruling in Hinckley's favor (Yoong, 2012). This raises an important question: should laws be reworded or changed simply because of an incident involving a prominent personality or high-profile politician?
References
Asokan, T. (2007). Daniel McNaughton (1813–1865). Indian Journal of Psychiatry, 223–224.
Biography.com Editors. (2017, April 28). John Hinckley Jr. Biography.com. Retrieved from https://www.biography.com/people/john-hinckley-jr-17171774
Cassel, E. (2006, July 28). The second Andrea Yates verdict. Retrieved from CounterPunch: http://www.counterpunch.org/2006/07/28/the-second-andrea-yates-verdict/
Dunham, N. (2016, June 20). Andrea Yates, in a mental facility, watches videos of her children — 15 years after she drowned them. Retrieved from People Crime: http://people.com/crime/andrea-yates-15-years-after-drowning-five-children-in-a-texas-mental-facility/
Francone, E. (2016, July). Insanity defense. Retrieved from Cornell Law School: https://www.law.cornell.edu/wex/insanity_defense
Nau, M., McNiel, D., & Binder, R. (2012). Postpartum psychosis and the courts. Journal of the American Academy of Psychiatry and the Law, 318–325.
The Insanity Defense Among the States. (2017). Retrieved from FindLaw: http://criminal.findlaw.com/criminal-procedure/the-insanity-defense-among-the-states.html
The 'insanity defense' and diminished capacity. (2017, May 26). Retrieved from Cornell Law: https://www.law.cornell.edu/background/insane/insanity.html
WGBH Edu Foundation. (2014). A case of insanity. Frontline.
Yoong, G. (2012, April 11). Top 10 most notorious insanity defense cases. Retrieved from Listverse: http://listverse.com/2012/04/11/top-10-most-notorious-insanity-defense-cases/
Create your account
Always verify citation format against your institution’s current style guide requirements.