2.1 Insanity defense
6 min read•august 20, 2024
The insanity defense is a complex legal doctrine that excuses defendants from criminal responsibility if they were legally insane when committing a crime. It has evolved from early common law approaches to modern standards, balancing punishment and treatment in the criminal justice system.
Various tests and rules have been developed to determine legal insanity, including the , , and . States have adopted different standards, with some abolishing the defense entirely or offering alternatives like verdicts.
Insanity defense overview
- The insanity defense is a legal doctrine that excuses a defendant from criminal responsibility if they were legally insane at the time of the crime
- Insanity is a legal term, not a medical one, and the standards for determining insanity vary across jurisdictions
- The insanity defense is based on the idea that a person who is unable to understand the nature and consequences of their actions or distinguish right from wrong should not be held criminally responsible
Historical development of insanity defense
Early common law approaches
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- Early English common law recognized that a person who was "mad" or "lunatic" should not be held criminally responsible
- The "wild beast" test excused a defendant if they were totally deprived of reason and understanding, similar to a wild beast
- The "good and evil" test excused a defendant if they could not distinguish between good and evil at the time of the crime
M'Naghten rule
- Developed from the 1843 English case of Daniel M'Naghten who attempted to assassinate the British Prime Minister
- Under the M'Naghten rule, a defendant is not guilty by reason of insanity if, at the time of the crime, they were laboring under such a defect of reason from a disease of the mind as to not know the nature and quality of the act they were doing or, if they did know it, they did not know what they were doing was wrong
- Focuses on the defendant's cognitive ability to understand the nature and wrongfulness of their actions
Irresistible impulse test
- Some jurisdictions supplemented the M'Naghten rule with the irresistible impulse test
- Under this test, a defendant is not guilty by reason of insanity if, by reason of mental disease or defect, they had an irresistible and uncontrollable impulse to commit the crime, even if they knew the act was wrong
- Recognizes that some mental disorders may impair a person's ability to control their actions, even if they understand the wrongfulness of the act
Durham product test
- The , adopted briefly by the D.C. Circuit in the 1950s, stated that a defendant is not criminally responsible if their unlawful act was the product of a mental disease or defect
- This test was criticized as too broad and was eventually abandoned in favor of other standards
ALI substantial capacity test
- The American Law Institute's Model Penal Code proposed the substantial capacity test
- Under this test, a person is not responsible for criminal conduct if, as a result of mental disease or defect, they lacked substantial capacity either to appreciate the criminality of their conduct or to conform their conduct to the requirements of the law
- This test combines the cognitive aspect of the M'Naghten rule with a volitional aspect similar to the irresistible impulse test
Modern insanity defense standards
Federal insanity defense
- The federal insanity defense, codified in the Insanity Defense Reform Act of 1984, is a modified version of the M'Naghten rule
- A defendant is not guilty by reason of insanity if, at the time of the crime, as a result of a severe mental disease or defect, they were unable to appreciate the nature and quality or the wrongfulness of their acts
- The Act places the burden of proof on the defendant to prove insanity by
State variations in insanity defense
- States have adopted various insanity defense standards, including the M'Naghten rule, the ALI substantial capacity test, and the federal insanity defense
- Some states have abolished the insanity defense altogether (Idaho, Kansas, Montana, Utah)
- Other states have adopted the guilty but mentally ill verdict as an alternative to the insanity defense (Michigan, South Carolina)
Burden of proof for insanity
Burden on defendant vs prosecution
- In most jurisdictions, the defendant bears the burden of proving insanity as an affirmative defense
- The prosecution must first prove all elements of the crime beyond a reasonable doubt, then the defendant must prove insanity by the applicable standard
- In a minority of states, once the defendant raises the issue of insanity, the prosecution must prove sanity beyond a reasonable doubt
Quantum of proof required
- The standard of proof for insanity varies by jurisdiction
- Some states require the defendant to prove insanity by a preponderance of the evidence (more likely than not)
- Other states, and the federal courts, require clear and convincing evidence of insanity (highly probable)
Scope of expert testimony
Ultimate issue rule
- Traditionally, expert witnesses were not allowed to testify as to the ultimate issue of whether the defendant was insane at the time of the crime, as this was seen as invading the province of the jury
- Modern rules of evidence, such as Federal Rule of Evidence 704, have abolished the ultimate issue rule and allow expert opinions on the ultimate issue of insanity
Limitations on expert opinions
- While experts can testify as to the ultimate issue, their testimony is still subject to other limitations
- Experts must base their opinions on scientifically valid principles and methods reliably applied to the facts of the case
- Courts may exclude expert testimony that is speculative, not based on sufficient facts or data, or not the product of reliable principles and methods
Consequences of successful insanity defense
Commitment to mental institution
- A defendant found not guilty by reason of insanity is typically committed to a mental health institution for treatment
- The length of commitment is indeterminate and depends on the defendant's continued dangerousness and mental health status
- Insanity acquittees can be committed for a period longer than the maximum sentence for the underlying offense
Release procedures after commitment
- Insanity acquittees can petition for release once they are no longer dangerous due to their mental illness
- The acquittee bears the burden of proving by a preponderance of the evidence that they are no longer dangerous
- If released, the acquittee may be subject to conditions and monitoring to ensure
Alternatives to insanity defense
Guilty but mentally ill verdict
- Some states have adopted the guilty but mentally ill (GBMI) verdict as an alternative to the insanity defense
- A GBMI verdict means the defendant is guilty of the offense but was mentally ill at the time of the crime
- A GBMI defendant is sentenced like any other offender but is supposed to receive mental health treatment while incarcerated
- Critics argue the GBMI verdict does not ensure effective treatment and may confuse juries
Diminished capacity defense
- The diminished capacity defense is distinct from the insanity defense and applies when a defendant's mental impairment prevents them from forming the specific intent required for the crime charged
- If successful, diminished capacity reduces the severity of the offense (first-degree murder to second-degree murder) but does not completely excuse criminal responsibility
- Not all jurisdictions recognize the diminished capacity defense
Policy considerations of insanity defense
Balancing punishment vs treatment
- The insanity defense reflects a balance between the goals of punishment and treatment in the criminal justice system
- It recognizes that some individuals are so mentally impaired that punishment serves no valid purpose and treatment is more appropriate
- Critics argue the insanity defense undermines personal responsibility and the deterrent effect of criminal law
Public safety concerns with release
- The release of insanity acquittees raises public safety concerns, particularly in high-profile cases
- While insanity acquittees must prove they are no longer dangerous due to mental illness to be released, there is always a risk of relapse or future violence
- Policymakers must balance the rights of insanity acquittees with the need to protect public safety
Potential for abuse of defense
- Some critics argue the insanity defense is prone to abuse by defendants feigning mental illness to avoid criminal responsibility
- However, the success rate of the insanity defense is quite low (less than 1% of cases) and defendants who "beat the rap" by reason of insanity often spend more time confined in a mental institution than they would have in prison if convicted
- Comprehensive mental health evaluations and the adversarial process help guard against fraudulent insanity claims
Key Terms to Review (18)
ALI Standard: The ALI Standard, set forth by the American Law Institute, refers to a legal test used to determine whether a defendant can be held criminally responsible for their actions based on their mental state at the time of the offense. This standard emphasizes the ability of the defendant to understand the nature of their actions and whether they could distinguish between right and wrong, connecting closely with the insanity defense in criminal law.
Ali Substantial Capacity Test: The Ali Substantial Capacity Test is a legal standard used to determine whether a defendant can be held criminally responsible for their actions based on their mental state at the time of the offense. It evaluates if the individual had substantial capacity to appreciate the wrongfulness of their conduct or to conform their behavior to the requirements of law. This test is significant in insanity defense cases, as it provides a framework for assessing the defendant's mental health and culpability, distinguishing it from other tests like the M'Naghten Rule.
Andrea Yates Case: The Andrea Yates case revolves around a tragic incident in 2001 when Andrea Yates drowned her five children in the family bathtub in Texas. This case is significant as it highlights the complexities of mental illness and the insanity defense, sparking widespread discussions on postpartum depression, psychosis, and legal standards for insanity in criminal cases.
Bipolar disorder: Bipolar disorder is a mental health condition characterized by significant mood swings that include emotional highs (mania or hypomania) and lows (depression). These shifts can affect energy levels, activity, sleep patterns, and the ability to think clearly. The relationship between bipolar disorder and the insanity defense is particularly relevant, as individuals experiencing severe episodes may be unable to understand the nature of their actions during a manic or depressive episode.
California's Proposition 8: California's Proposition 8 was a ballot initiative passed in November 2008 that sought to define marriage as a union between one man and one woman, effectively banning same-sex marriage in the state. This proposition highlighted significant societal debates surrounding marriage equality and the rights of LGBTQ+ individuals, leading to numerous legal challenges and discussions about the intersection of law and personal liberties.
Clear and Convincing Evidence: Clear and convincing evidence is a standard of proof that requires the evidence presented to be highly and substantially more likely to be true than not. This standard is often used in civil cases, particularly in matters like the insanity defense, where it is essential to demonstrate that a defendant had a mental illness at the time of the crime. It strikes a balance between the higher standard of 'beyond a reasonable doubt' used in criminal cases and the lower 'preponderance of the evidence' standard used in many civil cases.
Competency to Stand Trial: Competency to stand trial refers to a legal determination that assesses whether a defendant is mentally capable of understanding the charges against them and can participate in their defense. This involves evaluating the individual's mental state at the time of trial, ensuring they can comprehend court proceedings and assist their attorney. It is an essential aspect of the legal system that protects the rights of defendants and ensures fair trial processes, especially when considering mental health issues like those involved in the insanity defense.
Durham Rule: The Durham Rule is a legal standard used in the context of the insanity defense, which holds that a defendant is not criminally responsible if their unlawful act was the product of mental illness. This rule was established in 1954 by the case Durham v. United States and marked a shift towards a more inclusive understanding of mental health in legal contexts. It emphasizes the connection between mental illness and criminal behavior, allowing for a broader interpretation of insanity than previous standards.
Forensic psychologist: A forensic psychologist is a professional who applies psychological principles and techniques within the legal system, often assessing individuals involved in legal proceedings. This role includes evaluating the mental state of defendants, providing expert testimony in court, and advising legal professionals on psychological matters relevant to criminal cases. Their work often intersects with criminal law, particularly in cases involving the insanity defense, competency evaluations, and risk assessments.
Guilty but Mentally Ill: The term 'guilty but mentally ill' refers to a legal verdict where an individual is found to have committed a crime but is also recognized as suffering from a mental illness at the time of the offense. This verdict allows for the individual to be held accountable for their actions while also acknowledging their mental health condition, which can influence sentencing and treatment options. It balances the need for public safety with compassion for mental health issues, making it a unique outcome in the criminal justice system.
Irresistible Impulse Test: The irresistible impulse test is a legal standard used to determine whether a defendant should be held criminally responsible for their actions due to mental illness. This test assesses whether a person, due to a severe mental disorder, was unable to control their actions or conform their conduct to the law at the time of the crime. It highlights the balance between recognizing mental health issues and ensuring accountability for criminal behavior.
John Hinckley Jr. Case: The John Hinckley Jr. case refers to the legal proceedings surrounding Hinckley, who attempted to assassinate President Ronald Reagan in 1981. His trial was notable for its focus on the insanity defense, which ultimately led to a significant shift in how such defenses were viewed and applied in the U.S. legal system, raising questions about mental health, culpability, and public safety.
M'Naghten Rule: The M'Naghten Rule is a legal standard used to determine whether a defendant can be held criminally responsible for their actions due to insanity. Under this rule, a person may be excused from liability if, at the time of the offense, they were unable to understand the nature of their actions or did not know that their actions were wrong due to a severe mental disorder. This rule emphasizes cognitive impairment and moral understanding, shaping how insanity defenses are argued in court.
Preponderance of Evidence: Preponderance of evidence is a legal standard used in civil cases, requiring that the evidence presented by one side outweighs that of the other. This standard is met when it is more likely than not that a claim is true, tipping the scales in favor of one party. This concept is crucial for understanding how liability and defenses are evaluated in various legal scenarios.
Psychiatric evaluation: A psychiatric evaluation is a comprehensive assessment conducted by a mental health professional to determine an individual's mental health status, including their psychological functioning and the presence of any mental disorders. This evaluation often includes interviews, questionnaires, and standardized tests to gather information about the individual's thoughts, feelings, behaviors, and history. It plays a crucial role in cases where the insanity defense is raised, as it helps establish whether the defendant had the capacity to understand the nature of their actions at the time of the offense.
Public Safety: Public safety refers to the welfare and protection of the general public, often prioritized by government agencies to prevent crime, maintain order, and ensure community well-being. This concept is essential in evaluating various aspects of the criminal justice system, including mental health defenses and supervision strategies for offenders. By addressing public safety, authorities aim to create an environment where individuals can live without fear of harm, balancing individual rights with community interests.
Schizophrenia: Schizophrenia is a chronic and severe mental disorder that affects how a person thinks, feels, and behaves, often characterized by distortions in thinking, perception, emotions, language, and sense of self. Individuals with schizophrenia may experience delusions, hallucinations, and disorganized thinking, which can impact their ability to function in daily life. This condition is crucial in understanding the insanity defense, as it raises questions about an individual's mental state at the time of committing a crime.
Victim Advocacy: Victim advocacy refers to the support and assistance provided to victims of crime, helping them navigate the legal system, access resources, and cope with the emotional and psychological impacts of their experiences. This concept is crucial as it empowers victims by ensuring they have a voice in the justice process and promoting their rights. Victim advocates play a vital role in connecting victims with services such as counseling, legal assistance, and financial support, ultimately aiding their recovery and reintegration into society.