Also known as: diminished capacity · diminished-capacity defense · diminished capacity defences · diminished responsibility
Written by attorneys — see sources below.
Evidence of mental disease or defect short of legal insanity offered to show that a defendant lacked the mental state required for the charged offense or to mitigate culpability at sentencing.
David Dunn was charged with robbery after taking property from a store clerk. Dunn offered expert testimony that his mental disease prevented formation of the required specific intent. The court admitted the evidence on the mens rea element even though Dunn did not raise an insanity defense.
Darius Dixon was charged with murder after shooting a neighbor during an argument. Dixon offered expert testimony that his PTSD prevented formation of the intent to kill. The court admitted the evidence to rebut the prosecution's proof of the required mental state even though Dixon did not claim full insanity.
Brandon Joseph Williams, an Army veteran, was convicted by a jury of murdering Veta Karla Conrad, known as Karla. The jury assessed punishment at sixty-seven years' confinement and a $10,000 fine. Williams timely appealed to the Court of Appeals of Texas, Houston (14th Dist.). Karla and her daughter Sarah were living with Williams at the residence of his mother, Belinda Sue Williams, in Lake Jackson, Texas. Karla and Sarah shared Sue's bedroom while Sue slept on the living room couch and Williams had his own bedroom. On the night of the shooting, Williams, who had been using synthetic marijuana and methamphetamine, woke Sue and said he heard something outside. He told her to take Karla and Sarah into the bathroom, but Sue refused to avoid scaring them. Williams went through the kitchen and out the backdoor. Sue rose and saw him standing in the breezeway by the garage. He appeared startled, fell backwards, then raised and pointed his gun at her while advancing and yelling for her to get on the ground. Sue backed up, turned on a lamp, identified herself as his mother, and knelt on one knee. A single bullet from Williams's gun struck Karla, who had entered the room behind Sue. Sue tackled Williams, causing the gun to fly out of his hand, and held him down until police arrived after Sarah called 911. Approximately twelve hours after the shooting and after emergency medical treatment, Williams gave a recorded statement to investigators. In the statement he described seeing a figure, directing it to put its hands up and identify itself, and firing one round. He acknowledged shooting someone and described delusions and fighting with the devil. Williams tested positive for amphetamines and cannabis; the attending emergency room physician noted his heart rate, blood pressure, and respiratory rate were so elevated from the drugs that an abnormally high level of benzodiazepines was required. At trial Sue testified that she believed Williams had been suffering from PTSD or a flashback, though she had been unaware of his recent drug use in the house.
View caseDolores Diaz, age seventeen, was convicted of capital murder for a robbery homicide. At the penalty phase she introduced evidence of her immature brain development and limited capacity to appreciate consequences. The sentencer considered the evidence as mitigation and imposed life imprisonment rather than death.
In November 1999, fourteen-year-old Kuntrell Jackson and two other boys decided to rob a video store in Arkansas. En route, Jackson learned that one of the boys carried a sawed-off shotgun. Jackson initially stayed outside the store but later entered while the robbery was underway. When the clerk, Laurie Troup, refused to hand over money and threatened to call the police, one of Jackson's co-defendants shot and killed her. The three boys fled without taking any money. Arkansas prosecutors exercised their discretion to charge Jackson as an adult with capital felony murder and aggravated robbery. A jury convicted him of both offenses. The trial court imposed the statutorily mandated sentence of life imprisonment without the possibility of parole. Jackson did not challenge the sentence on direct appeal, and the Arkansas Supreme Court affirmed the convictions. In 2003, fourteen-year-old Evan Miller and a friend, Colby Smith, spent an evening drinking alcohol and smoking marijuana with Miller's neighbor, Cole Cannon, at Cannon's trailer in Alabama. After Cannon passed out, Miller stole his wallet. Cannon awoke and grabbed Miller by the throat. Smith struck Cannon with a baseball bat, and Miller then repeatedly hit Cannon with the bat. The boys set two fires in the trailer before leaving. Cannon died from his injuries and smoke inhalation. Miller had previously been in and out of foster care, regularly used drugs and alcohol, and had attempted suicide four times. Alabama law initially required that Miller be charged as a juvenile, but the district attorney sought and obtained removal of the case to adult court. A jury convicted Miller of murder in the course of arson. The trial court imposed the statutorily mandated sentence of life imprisonment without the possibility of parole. The Alabama Court of Criminal Appeals affirmed the conviction and sentence. Following this Court's decisions in Roper v. Simmons and Graham v. Florida, Jackson filed a state habeas petition arguing that his mandatory life-without-parole sentence violated the Eighth Amendment. The circuit court dismissed the petition, and the Arkansas Supreme Court affirmed. Miller's direct appeal was likewise unsuccessful. The Supreme Court granted certiorari in both cases.
View caseDeanna Davenport was charged with murder. She sought to introduce evidence of schizophrenia to show she lacked intent to kill. The trial court restricted the evidence to the insanity defense only and refused to allow it on the mens rea element.
In the early hours of June 21, 2000, Officer Jeffrey Moritz of the Flagstaff Police responded in uniform to complaints that a pickup truck with loud music blaring was circling a residential block. When he located the truck, the officer turned on the emergency lights and siren of his marked patrol car. This prompted petitioner Eric Clark, the truck’s driver (then 17), to pull over. Officer Moritz got out of the patrol car and told Clark to stay where he was. Less than a minute later, Clark shot the officer. The officer died soon after but not before calling the police dispatcher for help. Clark ran away on foot but was arrested later that day with gunpowder residue on his hands. The gun that killed the officer was found nearby, stuffed into a knit cap. Clark was charged with first-degree murder under Ariz. Rev. Stat. Ann. §13–1105(A)(3) for intentionally or knowingly killing a law enforcement officer in the line of duty. In March 2001, Clark was found incompetent to stand trial and was committed to a state hospital for treatment. Two years later the same trial court found his competence restored and ordered him to be tried. Clark waived his right to a jury, and the case was heard by the court. At trial, Clark did not contest that he shot the officer or that the officer died. He relied on his own undisputed paranoid schizophrenia at the time of the incident to deny that he had the specific intent to shoot an officer or knowledge that he was doing so. The prosecutor offered circumstantial evidence that Clark knew the victim was a police officer. The prosecutor also offered testimony indicating that Clark had previously stated he wanted to shoot police and had lured the victim to the scene to kill him. In presenting the defense case, Clark claimed mental illness. He sought to introduce it for two purposes. First, he raised the affirmative defense of insanity. This put the burden on himself to prove by clear and convincing evidence that at the time of the crime he was afflicted with a mental disease or defect of such severity that he did not know the criminal act was wrong. Second, he aimed to rebut the prosecution’s evidence of the requisite mens rea. Ruling that Clark could not rely on evidence bearing on insanity to dispute the mens rea, the trial court cited the Arizona Supreme Court’s decision in State v. Mott. That decision refused to allow psychiatric testimony to negate specific intent. It held that Arizona does not allow evidence of a mental disorder short of insanity to negate the mens rea element of a crime. As to his insanity, Clark presented lay testimony describing his increasingly bizarre behavior over the year before the shooting. This included testimony that Clark thought Flagstaff was populated with aliens trying to kill him and that bullets were the only way to stop them. A psychiatrist testified that Clark was suffering from paranoid schizophrenia with delusions about aliens when he killed the officer. The psychiatrist concluded that Clark was incapable of luring the officer or understanding right from wrong and was thus insane at the time of the killing. In rebuttal, the State’s psychiatrist gave his opinion that Clark’s paranoid schizophrenia did not keep him from appreciating the wrongfulness of his conduct before and after the shooting. The judge then issued a first-degree murder verdict. The judge found that Clark had not established that his schizophrenia distorted his perception of reality so severely that he did not know his actions were wrong. Clark moved to vacate the judgment and life sentence. He argued that Arizona’s insanity test and its Mott rule each violate due process. The trial court denied the motion. Affirming, the Arizona Court of Appeals held that the State’s insanity scheme was consistent with due process. The court read Mott as barring the trial court’s consideration of evidence of Clark’s mental illness and capacity directly on the element of mens rea. The Supreme Court of Arizona denied further review. The United States Supreme Court granted certiorari.
View caseDoris Duffy was tried for assault after attacking a stranger she believed was an alien. The defense offered psychiatric testimony that her paranoid schizophrenia negated the specific intent required for the charged offense. The court permitted the evidence on the mens rea issue.
On the evening of June 4, 1968, five white United States Marine Lieutenants in formal dress uniforms and a woman named Barbara Kelly entered a hamburger shop in Washington, D.C., around 2:40 a.m. after a night out. They ordered food at the take-out counter and noticed three Black men—appellants Alexander and Murdock and Cornelius Frazier—sitting at the other end of the counter. According to prosecution witnesses, a staring contest between Lieutenant Kramer and Alexander led to Alexander tapping Kramer on the shoulder, asking him to step outside, and making a threat. After a racial epithet from Lieutenant King, Alexander drew a .38 caliber revolver. Murdock then reentered and drew his own revolver, after which shots were fired, killing Lieutenants King and Lesnick and wounding Kramer and Kelly. Alexander, Murdock, and Frazier fled in Alexander's car, with Murdock firing additional shots from the window. They were stopped by police within a few blocks, and two revolvers were recovered from the car floorboard. Defense witnesses Frazier and Murdock testified that the Marines were drunk and aggressive, and Murdock claimed he fired in self-defense fearing for his life. At a joint jury trial in February 1969, both were convicted of carrying a dangerous weapon and four counts of assault with a dangerous weapon; Murdock was also convicted of two counts of second-degree murder. Murdock's trial was bifurcated; after the guilt phase, a separate hearing on criminal responsibility was held in November 1969 before the same jury, which found him criminally responsible. Alexander received consecutive sentences totaling five to twenty-three years, and Murdock twenty years to life. Both appealed their convictions to the United States Court of Appeals for the District of Columbia Circuit, which heard argument on December 21, 1970, and issued its decision on April 21, 1972.
View caseDanielle Dixon, convicted of capital murder, presented evidence of significantly subaverage intellectual functioning and adaptive deficits that began in childhood. The court held that the evidence established intellectual disability and therefore precluded imposition of the death penalty.
On February 21, 1978, Freddie Lee Hall and his accomplice Mark Ruffin kidnapped, beat, raped, and murdered Karol Hurst, a pregnant 21-year-old newlywed. Afterward Hall and Ruffin drove to a convenience store they planned to rob and killed Lonnie Coburn, a sheriff’s deputy who attempted to apprehend them. Hall received the death penalty for both murders, although his sentence for the Coburn murder was later reduced on account of insufficient evidence of premeditation. When Hall was first sentenced, this Court had not yet ruled that the Eighth Amendment prohibits States from imposing the death penalty on persons with intellectual disability. After this Court held that capital defendants must be permitted to present nonstatutory mitigating evidence in death penalty proceedings, Hall was resentenced. Hall then presented substantial and unchallenged evidence of intellectual disability, including school records in which his teachers identified him on numerous occasions as mentally retarded, testimony from his prior lawyer that he could not understand anything Hall said, and testimony from medical clinicians that Hall was significantly retarded and had levels of understanding typically seen with toddlers. Hall’s siblings testified that there was something very wrong with him as a child, that he was slow with speech and slow to learn, and that he walked and talked long after his other brothers and sisters. The sentencing court found substantial evidence that Hall had been mentally retarded his entire life yet still imposed a death sentence, which the Florida Supreme Court affirmed. In 2002, after this Court ruled that the Eighth Amendment prohibited the execution of persons with intellectual disability, Hall filed a motion claiming that he had intellectual disability and could not be executed. More than five years later, Florida held a hearing to consider Hall’s motion. Hall again presented evidence of intellectual disability, including an IQ test score of 71. Hall had received nine IQ evaluations in 40 years, with scores ranging from 60 to 80, but the sentencing court excluded the two scores below 70 for evidentiary reasons, leaving only scores between 71 and 80. In response, Florida argued that Hall could not be found intellectually disabled because Florida law requires that, as a threshold matter, Hall show an IQ test score of 70 or below before presenting any additional evidence of his intellectual disability. The Florida Supreme Court rejected Hall’s appeal and held that Florida’s 70-point threshold was constitutional. This Court granted certiorari.
View caseDiminished capacity evidence shows a mental disease or defect that negates the required mental state or mitigates culpability without establishing full legal insanity. Insanity is an affirmative defense that can result in acquittal by reason of insanity when the defendant is shown to lack criminal responsibility entirely.
Yes. In capital cases a defendant may introduce evidence that a mental disease or defect substantially impaired the capacity to appreciate the wrongfulness of the conduct or to conform conduct to law. The evidence is admissible as mitigation even if it does not meet the test for legal insanity.
Supporting sources
Jurisdictions typically require timely written notice of intent to rely on a mental disease or defect defense. The notice must alert the prosecution that mental state evidence will be offered so the state can prepare rebuttal experts, though the notice need not specify complete versus partial impairment.
Supporting sources
A defendant must disclose the intent to rely on mental-state evidence in advance of trial so the prosecution may obtain its own expert evaluation. Failure to provide timely notice may result in exclusion of the defense expert or a continuance to allow rebuttal preparation.
Supporting sources