The Supreme Court has recognized that the Eighth Amendment prohibits the imposition of the death penalty on certain groups whose diminished capacity renders them less morally culpable for their actions, even if they have the ability to discern right from wrong. In Atkins v. Virginia, the Supreme Court ruled that the intellectually disabled were one group. In Roper v. Simmons, the Court ruled that children under the age of 18 were another group. In doing so, the Court examined whether the execution of a child under the age of 18 or a person with an intellectual disability would further the penological justifications for the death penalty and concluded it would not in either case.

First, with respect to retribution, imposing the death penalty on a child or a person with an intellectual disability would not further the retributive reason for that punishment because the heart of retribution relates to a person’s culpability; persons with an intellectual disability and children who are under the age of 18 are less morally culpable. Nor is the goal of deterrence furthered. The “cognitive and behavioral impairments” of those with an intellectual disability and the traits of children whose characters and cognition are still developing, which make those groups less morally culpable, also make them less likely to take a potential punishment into account when they take actions.

These same considerations affect the propriety of imposing the death penalty on those who suffer from severe mental illness. Severe mental illness can impair one’s ability to make decisions and control impulses, through no choice of the afflicted person. Thus, like the groups exempted from the death penalty, persons with a severe mental illness have a diminished capacity and reduced moral culpability; imposing the death penalty on them would further neither retribution or deterrence.

In fact, the impairments of people who experience severe mental illness also make them more vulnerable to erroneous conviction. Persons with a severe mental illness are more vulnerable to police pressure, have an impaired ability to participate in their defense, and are poor witnesses due to their diminished perception of reality. They are therefore more susceptible to be wrongfully accused and convicted of a crime; thus, imposing the death penalty on a person with a severe mental illness can increase the risk that an innocent person will be executed.

Notwithstanding this, neither the federal constitution nor Texas law prohibits a death sentence from being imposed on a person who has a documented severe mental illness. If a person facing the death penalty or execution suffers from mental illness, that can affect the criminal proceedings against them in only a limited set of circumstances. And none of those circumstances address the question of whether a person’s severe mental illness renders them categorically less culpable for the offense they were convicted of. For example, both United States Supreme Court cases and Texas law provide that mental illness may render a defendant incompetent to stand trial. This requires a showing that he does not have the ability to consult with his attorney with a reasonable degree of rational certainty, or that he does not have a rational, as well as factual, understanding of the proceedings against him. Similarly, the United States Supreme Court has also held that Eighth Amendment prohibits states from executing prisoners whose mental illness renders them unable to rationally understand the reason the state seeks to execute them. If the person is restored to competency, the execution can be carried out notwithstanding whether—or how—their mental illness impacted their moral culpability.

Likewise, the Texas Penal Code provides an affirmative defense to a defendant at the guilt/innocence phase of his trial: a defendant may assert that, as a result of mental disease or defect, he did not know that his conduct was wrong. If the judge or jury determines that a person is not guilty by reason of insanity, the defendant is considered acquitted. However, if a jury finds that the defendant did not meet the high bar of showing that he did not know his conduct was wrong, he will still be found guilty of capital murder and eligible for a death sentence—even if the jury believes the person suffers from severe mental illness. Categorical protection against the death penalty for persons with severe mental illness would protect against the vulnerabilities that population shares with other groups who the Supreme Court has determined cannot be sentenced to death consistent with the Eighth and Fourteenth Amendments.

In 2019, the Texas Legislature considered legislation that would have precluded imposition of the death penalty on persons with severe mental illness. This legislation proposed that persons who had a qualifying medical diagnosis or documented symptoms of a narrow category of mental illness—namely, schizophrenia, schizoaffective disorder, or bipolar disorder—would receive a sentence of life without the possibility of parole in a capital murder case, rather than the death penalty. Although this legislation passed the Texas House, the Texas Senate failed to take the measure up.

Intellectual disability is characterized by significant deficits in both intellectual and adaptive functioning that manifest during the developmental period. Adaptive functioning refers to “how well a person meets community standards of personal independence and social responsibility, in comparison to others of similar age and sociocultural background.”[1] It is estimated that approximately 1 to 2 percent of the U.S. population has an intellectual disability. Intellectual disability can be classified as mild, moderate, severe, or profound. The vast majority of people with an intellectual disability are mildly intellectually disabled, but even a person with a mild intellectual disability has significant impairments in functioning. But people who have an intellectual disability can still be employed, live independently, and get married and have a family, especially with the right support system in place.

In Atkins v. Virginia, decided in 2002, the United States Supreme Court held that the execution of people who have an intellectual disability is cruel and unusual punishment, thereby violating the Eighth and Fourteenth Amendments. The Court reasoned, “Because of their disabilities in areas of reasoning, judgment, and control of their impulses, . . . [intellectually disabled people] do not act with the level of moral culpability that characterizes the most serious adult criminal conduct.”

To date, the Texas legislature has not enacted any laws to give effect to the Atkins decision, leaving it to Texas’s highest criminal state court, the Court of Criminal Appeals, to develop the criteria for evaluating intellectual disability in death penalty cases in Texas. The Court of Criminal Appeals responded to Atkins in a 2004 decision called Ex parte Briseno by adopting a stereotype-laden definition of intellectual disability, including announcing a set of unscientific factors (which would come to be known as the “Briseno factors”) to determine whether a capital defendant’s intellectual disability met the level and degree required to exempt him or her from the death penalty. Along with being criticized for setting out the Briseno factors (which had no basis in any diagnostic criteria to evaluate intellectual disability), the case became infamous for its reference to the character Lennie from John Steinbeck’s Of Mice and Men, implying that a person who appeared to a lay person to be less impaired than that fictional character would not be considered ineligible for the death penalty in Texas. The effect of Texas’s standard was to exempt only the most profoundly intellectually disabled defendants from the death penalty.

Thirteen years after Briseno, the Supreme Court agreed to hear a case challenging the way Texas assessed capital defendants for intellectual disability in Moore v. Texas (Moore I). A state district court had recommended that Bobby Moore, a man on Texas’s death row, should be found intellectually disabled and ineligible for the death penalty. The Texas Court of Criminal Appeals denied habeas corpus relief—overruling the district court’s recommendation that relief be granted—because, in the CCA’s view, Mr. Moore did not qualify as intellectually disabled under Briseno. In Moore, the Supreme Court struck down many aspects of the CCA’s Atkins implementation scheme because it failed to adequately identify persons with intellectual disability.

The Supreme Court held in Moore that state courts’ Atkins implementation procedures must reflect “current medical standards,” and that Texas’s did not. According to the Supreme Court, the procedures adopted by the CCA reflected outdated clinical standards, and, more egregiously, were based on lay stereotypes of intellectual disability, “drawing no strength from [the Supreme Court’s] precedent.” The Supreme Court especially criticized the CCA’s reliance on the Briseno factors, describing them as “an invention of the CCA untied to any acknowledged source” and “[n]ot aligned with the medical community’s information.” Damningly, the Supreme Court concluded that Texas’s implementation of the Atkins decision “[b]y design and in operation, . . . creat[ed] an unacceptable risk that persons with intellectual disability will be executed."

Between 2002, when Atkins was decided, and 2017, when Moore corrected the CCA’s troublesome application of it, Texas executed 264 people, many of whom had claims of intellectual disability that were adjudicated under the standard held by the Supreme Court to have created an unacceptable risk that persons with an intellectual disability would be executed.

There are still ongoing issues with how courts and legislatures make and apply standards for determining intellectual disability. Even after the Supreme Court struck down the CCA’s standard for reviewing intellectual disability claims, the CCA nevertheless upheld Mr. Moore’s death sentence again. The Supreme Court took Mr. Moore’s case a second time and held that the CCA had committed many of the same errors on remand. In the Supreme Court’s second decision in Mr. Moore’s case, it directed the CCA to find Mr. Moore intellectually disabled.

Even after Moore, the Texas legislature has not enacted a statute establishing standards and procedures for determining whether a capital defendant is exempt from the death penalty due to an intellectual disability. In 2019, Texas Defender Service advocated for the enactment of legislation that would codify procedures for sentencing a person with intellectual disability in a capital case. The legislation did not pass, and courts continue to develop ad hoc procedures and make inconsistent findings where an intellectual disability is implicated. TDS also continues to vigorously litigate Atkins claims in Texas courts to try to ensure that courts are faithfully applying appropriate standards and procedures to eliminate the risk that persons with an intellectual disability will be executed in the state of Texas.

[1] American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-V), at 37.

Law of Parties

The law of parties is a theory of vicarious liability that allows defendants to be held criminally liable for offenses committed by others, as if they had committed the offense themselves. In Texas, this statute has been used to convict persons of capital murder and impose death sentences, even when the defendant did not kill or intend to kill another person.

Generally, to obtain a capital murder conviction in Texas, a jury is required to find that a person committed an intentional or knowing murder. Texas, however, allows for the law of parties to depart from the intent requirement. For example, a defendant who enters a conspiracy to commit one felony, like burglary, may be held liable for an intentional homicide committed by a co-conspirator, notwithstanding that the defendant had no intention that any person would be harmed.

Of 52 jurisdictions, including Washington, D.C., and the federal government, 36 have issued legislative or judicial decisions rejecting imposition of the death penalty for people who neither killed nor intended to kill. [1] According to the Death Penalty Information Center, it is aware of only 11 individuals who did not intend to kill and have been executed in the modern era.

When the Supreme Court originally upheld the constitutionality of Texas’s death penalty scheme in 1976’s Jurek v. Texas, it did so under the premise that a defendant would be death eligible only if he intended to commit a homicide. The holding was based on the then-new Texas Penal Code, which “narrowed the scope of its laws relating to capital punishment.” Specifically, the Supreme Court understood the Texas Penal Code in effect at that time to “limit[] capital homicides to intentional and knowing murders committed in five situations: murder of a peace officer or fireman; murder committed in the course of kidnapping, burglary, robbery, forcible rape, or arson; murder committed for remuneration; murder committed while escaping or attempting to escape from a penal institution; and murder committed by a prison inmate when the victim is a prison employee.”

The decision was also based on a sentencing procedure that differed from the current one. Following a guilty verdict for a capital murder charge, the jury must consider special issues to determine whether the defendant will receive a life sentence or the death penalty. Under the law at the time that Jurek was decided, Texas juries were required to find, before a death sentence could be imposed, that “the conduct of the defendant that caused the death of the deceased was committed deliberately and with the reasonable expectation that the death of the deceased or another would result.” The Supreme Court in Jurek observed that, although Texas had not adopted a list of statutory aggravating circumstances, the existence of which can justify the imposition of the death penalty (as other states had done), “its action in narrowing the categories of murders for which a death sentence may ever be imposed serve[d] much the same purpose.”

Today, the statute has changed. As former Texas Court of Criminal Appeals Judge Alcala recently observed in Ex parte Murphy,

The capital-murder statute provides for around one hundred different ways that a person can be convicted of capital murder. The list of ways in which a person may commit capital murder is twice as long when one considers that a defendant may be convicted not only as a principal actor, but also as a party by, for example, aiding or attempting to aid another person to commit the offense. And the list is thrice as long when one considers that a defendant may be convicted of capital murder even if he lacked any intent to commit that offense but was part of a conspiracy to commit a felony under certain circumstances.

When the Supreme Court decided Jurek, it did not consider the impact of Texas’s law of parties when it held that Texas’s death penalty scheme protected against arbitrariness. Indeed, it understood the scheme to be limited to those who “intentional[ly] and knowing[ly]” committed murder. Moreover, the decision was also based on a sentencing procedure that differed from the current one. Specifically, the special issues then required the jury to find, before a death sentence could be imposed, that “the conduct of the defendant that caused the death of the deceased was committed deliberately and with the reasonable expectation that the death of the deceased or another would result.” That special issue effectively precluded persons who did not intend to commit murder under the law of parties from being sentenced to death because it required the jury to find both that the individual caused the death and that the conduct causing it was deliberate. That special issue was repealed in 1993, and the Texas scheme no longer requires a jury finding that the conduct of the defendant that caused the death of the deceased was committed deliberately. Under current Texas law, after a defendant has been found guilty as a party to an offense, he can be sentenced to death for merely “[a]nticipating that a human life will be taken.”[2] As former CCA Judge Alcala has observed, this standard does not meet the level of culpability needed constitutionally to impose a death sentence.

The Supreme Court has addressed the constitutionality of the death penalty for people who did not kill or intend to kill in Enmund v. Florida and Tison v. Arizona. The rule created by these cases prohibits the imposition of the death penalty on such defendants unless the defendant was a “major participant” in felonious activity and displayed “reckless indifference to life.” Nevertheless, Texas’s law of parties permits juries to give death sentences to people without regard to whether they killed, intended to kill, were major participants in felonious activities, or displayed a reckless indifference to human life—all in clear violation of the Eighth Amendment.

It has been long recognized that the death penalty should be reserved “for the worst of the worst.” Texas, however, applies the law of parties in a way that so broadens the categories of behavior eligible for a death sentence as to render its capital punishment arbitrary. When Tison was decided, the Supreme Court took into consideration its belief that the majority of American jurisdictions authorized the death penalty where accomplices had at least a reckless disregard for life and were major participants. Now, that is no longer true. Societal consensus and the outcomes of capital trials show decreasing interest in the death penalty and death sentences for those who never killed or intended to kill, further supporting the need to eliminate the power of prosecutors to obtain death sentences premised on Texas’s law of parties, which permits convictions for capital murder without the State proving an intent to kill.

[1] See Joseph Trigilio & Tracy Casadio, Executing Those Who Do Not Kill: A Categorical Approach to Proportional Sentencing, 48 Am. Crim. L. Rev. 1371, 1374, 1401 n.280 (2011) (identifying thirty-three jurisdictions in 2011, including the seventeen jurisdictions had banned the death penalty for everybody). Since the publication of the article, five more states have abolished the death penalty, but before abolition, two of those jurisdictions did not permit executions of people who did not kill or intend to kill.

[2] Ladd v. State, 3 S.W.3d 547, 573 (Tex. Crim. App. 1999) (emphasis omitted).

Texas is the only state in which imposition of the death penalty requires a jury to predict how the defendant will behave in the future. Under Texas’s capital murder statute, the first question jurors must answer in every case where the State is seeking a death sentence is whether “there is a probability that the defendant would commit criminal acts of violence that would constitute a continuing threat to society.” This is often referred to as the “future dangerousness” special issue. The burden is on the State to prove future dangerousness beyond a reasonable doubt.

In Jurek v. Texas, even while it recognized the difficulty of predicting future behavior, the United States Supreme Court upheld the constitutionality of Texas’s death penalty scheme, including the requirement that juries must decide whether a defendant is likely to commit violent acts in the future. In Barefoot v. Estelle, the Supreme Court rejected arguments that expert testimony about future dangerousness is too unreliable to be admitted as evidence for a jury to consider. Yet, in practice, the evidence relied on by the State to meet its burden of establishing future dangerousness is fraught with reliability problems and lends itself to inherent biases about who in society is considered dangerous.

Prosecutors often rely on “experts” to predict a defendant’s future behavior—despite the significant questions about the accuracy and reliability of this type of testimony. Indeed, the American Psychological Association has condemned the type of methodology often used in Texas capital cases as unscientific and unreliable and even expelled an “expert” on future dangerousness on whom Texas prosecutors relied in multiple capital cases. Nicknamed “Dr. Death” for his propensity find future dangerousness in his cases, Dr. James Grigson routinely testified for the prosecution that a given defendant would present a future danger—sometimes testifying that a person would kill again with “100% certainty”—without ever even meeting or examining the defendant. Even after being informed that a study concluded that people whom Dr. Grigson had deemed a future danger were not engaging in assaultive behavior, Dr. Grigson continued to posit the future dangerousness of defendants for years. And despite the mountain of evidence of the unreliability of Dr. Grigson’s testimony, Texas courts continue to deny relief to people whom Dr. Grigson helped send to death row.


The future dangerousness question also creates a risk that Texas juries will impermissibly rely on a defendant’s race in making their determination. In fact, Texas prosecutors have relied on the testimony of experts who have expressed opinions about a defendant’s future dangerousness that were based in part on the defendant’s race, including “expert” testimony that explicitly opined that black and Hispanic men are more likely than white men to behave violently. In 2017, TDS won a case before the United States Supreme Court reversing Duane Buck’s death sentence because an expert testified that Mr. Buck was more likely to act violently in the future because he is black. The Supreme Court noted that such testimony coming from an expert was “potent evidence” of Mr. Buck’s future dangerousness because the expert’s testimony “appealed to a powerful racial stereotype—that of black men as ‘violence prone.’” The Supreme Court held that Mr. Buck’s death sentence must be overturned because the jury’s sentencing determination had been impermissibly tainted by that “particularly noxious strain of racial prejudice,” which coincided with the “central question at sentencing.” As the Court noted, “some toxins can be deadly in small doses.” While the decision in Buck struck down testimony explicitly relying on racial stereotypes to prove future dangerousness, much work remains to be done to address how the same racial stereotypes and implicit bias can influence a jury’s assessment of whether someone is likely to be dangerous in the future.

Additionally, it is frequently the case that persons remain on Texas’s death row for years, even decades, before they are executed. Yet Texas’s capital sentencing statute provides no mechanism to reevaluate a determination of future dangerousness rendered at a defendant’s trial, despite it being a fundamental precept of due process that government actions restraining life and liberty that are based on forward-looking predictions must be periodically reassessed. Thus, a person could remain on death row without incident for decades and still be executed based on a stale, decades-old prediction of his being a “future danger” that took into account circumstances that may no longer even exist (like the defendant’s age, fitness, mental health, etc.) at the time the state seeks to actually execute the individual. When time has either made stale—or demonstrably proven wrong—a judgment that was based on a prediction of the future, there is no reasonable justification for relying on that judgment to execute the person.


Despite the significant problems with requiring juries to predict an individual’s future dangerousness, Texas continues to require this determination in death penalty cases. courts also continue to refuse to halt executions in cases where such testimony was utilized.

In 2009, the National Academy of Sciences issued a report that concluded, “[w]ith the exception of nuclear DNA analysis . . . no forensic method has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source.” In 2016, the President’s Council of Advisors on Science and Technology issued a report that identified, among other things, bite mark comparison evidence, shoeprint evidence, and firearms evidence as lacking “foundational[] valid[ity].”[1] Many of these methodologies, however, continue to be admitted in court despite criticism from the scientific community.

Moreover, there are people on Texas’s death row whose convictions were based on now thoroughly debunked scientific testimony. In 2013, Texas was the first state to provide a way for people to challenge wrongful convictions that were based on flawed or discredited forensic science when the legislature enacted Article 11.073 of the Code of Criminal Procedure. This law is an important lifeline for people sentenced to death. But while the availability of this provision has been used successfully to grant access to further proceedings, to date, no one sentenced to death has been granted a new trial due to the unreliability of purportedly scientific testimony that undergirded their conviction. As such, this statute does not offer absolute protection for those with convictions based on faulty science and more can be done to protect people who have been wrongfully convicted.

Additionally, although many people have been—and continue to be—sentenced to death on the basis of evidence that has been recognized as unreliable, in Ex parte White, the Texas Court of Criminal Appeals held that Article 11.073 can only be used to challenge science introduced at the guilt/innocence phase of the trial. This means that the remedy provided by the legislature is inaccessible to people sentenced on the basis of untrustworthy science—even those who should be constitutionally ineligible for the death penalty due to intellectual disability, or those who were sentenced to death based on an unreliable predictor of future dangerousness. In a concurring opinion in White, Judge Richardson, joined by Judges Hervey and Newell, noted that this was “a harsh result, particularly in a death penalty case where the jury is often asked to evaluate expert scientific testimony and scientific evidence in assessing whether the death penalty is the proper punishment,” and called upon the Legislature to fix the statute. Texas Defender Service has advocated in the Legislature to eliminate this barrier to sentencing relief but the statute has not yet been modified to include claims that the State relied on junk science to obtain a death sentence.

Finally, the institutions tasked with handling forensic analysis can contribute to unreliable and unfair convictions. Texas is no stranger to this; several notable crime laboratory scandals have occurred across the state. In 2012, the Texas Forensic Science Commission discovered that a technician in the Department of Public Safety crime lab in Houston had falsified results in many drug cases, which could have affected almost 5,000 convictions in 30 counties. In 2017, an investigation of the Austin Police Department’s crime lab revealed that lab staff had been using outdated and unsound procedures resulting in the use of unreliable DNA evidence in thousands of cases, including a capital case.

More can be done to stop the influence of false or misleading forensic science in criminal trials. Given that unreliable junk science has contributed to at least 160 wrongful convictions in Texas, the emphasis should be on science and the accuracy—not the finality—of convictions.

[1] Jim Hilbert, The Disappointing History of Science in the Courtroom: Frye, Daubert, and the Ongoing Crisis of "Junk Science" in Criminal Trials, 71 Okla. L. Rev. 759, 804 (2019) (citing President's Council of Advisors on Sci. & Tech., Exec. Office of the President, Forensic Science in Criminal Courts: Ensuring Scientific Validity of Feature-Comparison Methods, at 1 (2016))