The insanity defense has a long history in the United States' criminal justice system. Although it is rarely used and has a low success rate, understanding how it works provides broader insight into criminal defense strategies.
In certain cases, the insanity defense is a valid and necessary legal protection. If you have been charged with any type of crime, an experienced Killeen criminal defense attorney can help you choose the perfect defense strategy for your case.
If you have questions about mental health defenses in Texas, contact our office today to discuss your options with a knowledgeable attorney.
The History of the Insanity Defense
According to The Washington Post, the history of the insanity defense traces back to 1843 in London. A woodworker named Daniel M’Naghten believed he was the target of a conspiracy involving the British Prime Minister, Robert Peel, and the Pope.
M’Naghten set out to assassinate Peel but accidentally killed his secretary instead. At trial, psychiatrists testified that M’Naghten was delusional. The jury ultimately found him not guilty by reason of insanity.
The Standard Set
The public was outraged by the verdict. A year later, a panel of British judges established the legal standard still used today. For the insanity defense to apply, the defendant must have suffered a "defect of reason from disease of the mind" such that they did not understand what they were doing or did not know it was a crime.
Over time, the burden of proof has shifted. Historically, the prosecution had to prove a defendant's sanity. Today, it is the defense’s responsibility to prove insanity for the defense to succeed.
The Reason Behind the Insanity Defense
The insanity defense serves as a safeguard in the criminal justice system. While most criminal charges rely on factual evidence, the insanity defense introduces a moral and medical perspective.
In rare but significant cases, it allows a jury or judge to determine that a person who committed a crime was not legally or morally responsible due to severe mental illness.
If your loved one is facing charges and struggling with mental illness, let us help you understand the legal protections available. Schedule a FREE consultation to discuss your case.
The Tests Used to Determine Severe Mental Disease
Some states, including Kansas, Montana, Idaho, and Utah, have eliminated the insanity defense altogether. Others have implemented alternative standards, such as diminished capacity or a verdict of guilty but mentally ill.
In states that permit the insanity defense, one of four primary legal tests applies.
If a defendant has been diagnosed with a serious mental illness, such as schizophrenia, intellectual disability, or paranoia, he or she may be able to demonstrate legal insanity using one of the following tests, each of which applies a different legal standard:
The Irresistible Impulse Test
Under this test, a defendant may understand that their actions were wrong but be unable to control their behavior due to mental illness.
The M’Naghten Defense
Often called the "right or wrong" test, the M’Naghten standard requires proof that the defendant did not understand the nature of the act or that it was wrong due to their mental illness. This is the standard used in Texas.
The Substantial Capacity Test
The substantial capacity test focuses on whether the defendant lacked the mental capacity either to appreciate the criminality of their conduct or to conform their behavior to the law.
The Durham Rule
Only used in New Hampshire, the Durham test holds that a defendant is not criminally responsible if the unlawful act was a product of mental illness.
Insanity Defense vs. Diminished Capacity
The insanity defense is considered a full affirmative defense. The defendant admits to the act but argues that mental illness excuses the behavior. A successful defense leads to a not guilty verdict.
Diminished capacity, on the other hand, is a partial defense. It may reduce the severity of the charges or sentence but does not result in full acquittal.
If you are unsure whether diminished capacity or insanity applies in your case, contact a criminal defense attorney. Our defense attorneys can clarify your options and defend your rights.
The Insanity Defense in Texas
In Texas, the insanity defense must be asserted early in the legal process, typically in the defendant’s original answer to the charges.
Texas follows the M’Naghten Rule. The defense must show that the defendant did not understand that their actions were wrong or illegal due to a severe mental disease or defect. A clear causal link between the mental illness and the conduct must be demonstrated.
Mens Rea and Its Role
Mens rea is Latin for "guilty mind" and is a fundamental element in most criminal offenses. Prosecutors must prove that the defendant had criminal intent.
For example, a person who trips and accidentally damages property lacks intent, whereas someone who deliberately causes damage can be charged with a crime.
If a defendant does not have criminal intent due to a mental illness, the insanity defense may be applicable. However, proving a lack of intent is challenging and usually inferred from the defendant's behavior and mental state.
Competency to Stand Trial vs. Insanity Defense
The insanity defense pertains to the defendant's mental state at the time of the offense. In contrast, competency to stand trial refers to their mental condition during the legal proceedings.
A defendant must understand the charges against them and be able to assist in their defense. If not, the court will postpone the trial until competency is restored.
The Rarity of the Insanity Defense
A comprehensive study reported by The Washington Post examined the use of the insanity defense across eight states. It found that less than 1% of defendants plead insanity, and only about 25% of those succeed.
Despite its rarity and low success rate, the insanity defense remains an important option for defendants with severe mental illness.
According to the American Academy of Psychiatry and the Law, most successful cases involve individuals with serious psychiatric conditions that leave them significantly impaired.
What Happens When the Defense Succeeds?
Not guilty verdicts by reason of insanity do not result in defendants being released. Instead, they are committed to a state psychiatric facility.
They remain hospitalized until mental health professionals determine that they are no longer a danger to themselves or others. In some cases, this confinement can exceed the length of a prison sentence.
If you have more questions about what happens if someone is found not guilty by reason of insanity, talk to us about outcomes, treatment, and future legal implications.
The Andrea Yates Case
One of the most well-known insanity defense cases occurred in Texas in 2001. Andrea Yates drowned her five children while suffering from severe postpartum psychosis.
Her husband left home around 9 a.m., and by 10 a.m., all five children were dead. She called 911, then her husband, stating, "It’s time," referencing a biblical belief in Armageddon.
Yates had a documented history of psychiatric illness. She had been hospitalized multiple times for severe postpartum depression, psychosis, and suicidal thoughts, often focused on her children.
Her First Trial
In 2002, Yates faced a death-qualified jury in Harris County, one of the nation’s most aggressive death penalty jurisdictions. A death-qualified jury is made up of jurors who will consider imposing the death penalty if the facts support it.
She was convicted of capital murder after less than four hours of deliberation. The jury rejected the death penalty and sentenced her to life in prison, with parole eligibility after 40 years.
Her Second Trial
The conviction was overturned due to false testimony by a prosecution expert who incorrectly stated that an episode of Law and Order featuring a similar crime aired before Yates committed her crime.
In her 2006 retrial, with a non-death-qualified jury, Yates was found not guilty by reason of insanity after 12 hours of deliberation. The jury foreman later explained that although Yates knew the act was legally wrong, they believed she thought it was right within her delusional framework.
Public Misconceptions About the Insanity Defense
The psychiatrist who testified in Yates’ case noted that the public is highly skeptical of the insanity defense. Many people fear that defendants may fake mental illness.
There is also a common belief that a successful insanity defense means the defendant escapes punishment. In reality, most spend more time confined in psychiatric facilities than they would have in prison.
High-profile media coverage contributes to the false perception that the defense is used frequently and successfully. In truth, the insanity defense is rare and is held to a high legal standard.
Consult a Killeen Criminal Defense Attorney
The insanity defense is complex, rarely successful, and deeply misunderstood. Yet it plays a vital role in ensuring justice for defendants with serious mental illness.
If you or a loved one is facing criminal charges and mental illness is a factor, contact Brett Pritchard at the Law Office of Brett H. Pritchard.
Call us at (254) 781-4222 or schedule your FREE consultation online today.