Capital Mitigation

Capital mitigation consists of evidence that is presented in a death penalty trial to obtain a sentence other than death. In the bifurcated trial process that characterizes modern capital cases (in which a second penalty or sentencing phase occurs only if the defendant has been convicted of a crime for which the death penalty may be imposed), mitigation typically is introduced in the second stage of the trial. Its purpose is to lessen the jury’s perceived need, desire, or rationale to return a death verdict. Under the death penalty statutes that govern most states, jurors are instructed to “weigh” mitigating factors (which lessen the tendency to punish with death) against aggravating factors (which increase that tendency).

Nature and Scope of Capital Mitigation

The scope of potential mitigation in a capital case is quite broad. In fact, unlike aggravating factors, which typically are limited in capital-sentencing statutes to certain prescribed categories of evidence (such as prior felony convictions), mitigating factors or evidence has been repeatedly defined by the courts as consisting of “anything proffered by the defendant in support of a sentence less than death.”

Conceptually, mitigation falls into several broad categories. Capital defense attorneys often seek to introduce evidence and testimony that tend generally to humanize the defendant—that is, to emphasize the defendant’s personhood and establish points of commonality between the defendant and the jurors who sit in judgment and decide his or her fate. Because many jurors enter the courtroom with stereotypic views of violent criminality, defense attorneys seek to overcome preexisting tendencies to demonize or pathologize the defendant in ways that will facilitate condemning him or her to death. Mitigating evidence that humanizes the defendant challenges the notion that extreme violence is perpetrated only by dehumanized, anonymous figures or human monsters rather than real people with very problematic and troubled lives.

Capital mitigation can provide jurors with a broader and more nuanced view of the causes of violence and deepen their understanding of the person whose life they are being asked to judge. In addition to the introduction of mitigating evidence that generally humanizes the defendant, defense attorneys also typically introduce background or social history testimony that places the defendant’s life in a larger social and developmental context. Background and social history testimony can be used to explain the various ways in which the nature and direction of a defendant’s life have been shaped and influenced by events and experiences that occurred earlier, often in childhood. This may include childhood trauma, parental mistreatment, and exposure to other developmental “risk factors” that are known to increase the likelihood that someone will engage in criminal behavior later in life.

The presentation of a mitigating social history in a capital penalty trial also may include testimony about broader community-based risk factors and larger sociological forces to which the defendant was exposed and that helped shape his or her life course. Poverty, racism, “neighborhood disadvantage” (the surrounding environments characterized by unemployment, instability, and crime), and other social contextual factors may help explain the patterns of criminal behavior in which the defendant engaged. In that sense, they represent a form of mitigation. Similarly, testimony about mental health problems or disorders from which the defendant suffered, his or her cognitive limitations or deficits, or evidence of neurological abnormalities— especially if they help account for criminal behavior— are mitigating in nature. Capital mitigation also may focus on the circumstances that led up to, or helped precipitate, the capital crime itself. That is, showing that the crime was the product of a unique set of situational forces or circumstances that are unlikely to recur—at least in a prison setting (where a capital defendant who is not sentenced to death will be sent)—is a form of mitigation.

Another common but very different category of mitigation includes testimony about a capital defendant’s positive qualities, good deeds, or accomplishments or the defendant’s potential to make useful contributions in the future. Often this includes evidence of the defendant’s positive (or, at least, unproblematic) adjustment to prison in the past, testimony about his or her potential to adjust well in the future, and even evidence that the defendant is likely to make useful contributions to prison life during his or her long-term incarceration. In these instances, the nature of the mitigating significance of the evidence derives from demonstrating the complexity of human nature (i.e., that even people who have done very bad things have other positive qualities that are unrelated to their criminality) and reminding jurors that even persons convicted of a very serious violent crime can make contributions to others that would be lost if they were sentenced to death.

In sum, the structure of capital mitigation generally involves the message that the defendant is a person, there are reasons why his or her life took the course that it did (ones that involve powerful psychological and sociological forces over which the defendant had little or no control), and the positive qualities and future contributions of the defendant would be sacrificed if he or she were to be sentenced to death.

Legal Doctrines Governing Capital Mitigation

The explicit use of mitigation as a key element in the death-sentencing process was first acknowledged by the U.S. Supreme Court in Gregg v. Georgia (1976) and its companion cases. Here, the Court approved a number of new state death-sentencing statutes that had been enacted in response to the Court’s earlier declaration in Furman v. Georgia (1972) that the death penalty was unconstitutional as it was then being applied in the United States. The Gregg opinion endorsed a framework for capital sentencing that appeared in several of the revised state death penalty statutes that the Court reviewed and that was derived from the American Law Institute’s Model Penal Code (1962). The Model Penal Code provided a list of mitigating and aggravating circumstances that it suggested jurors should “take into account” in deciding whether to impose a death sentence. The Court endorsed this approach as an acceptable way to attempt to guide the discretion of the jury.

Two years after Gregg, in Lockett v. Ohio (1978), the Supreme Court provided an expansive interpretation of the scope of admissible capital mitigation, indicating that the sentencer in a death penalty case (at that time, either a judge or a jury) must “not be precluded from considering,” as mitigating factors, “any aspects of a defendant’s character…that the defense proffers as a basis for a sentence less than death.” In a long line of cases that followed, the Court continued to endorse the principle that capital defendants should be permitted to introduce a very broad (indeed, seemingly limitless) range of mitigating evidence. These opinions repeatedly established the right to introduce a wide range of mitigating evidence by declaring unconstitutional any statutes, procedures, or rulings that precluded or limited defendants from doing so. However, the Court nonetheless failed to impose any requirement, standard, or guideline governing whether and when capital attorneys should introduce mitigating testimony (or what remedy, if any, defendants were entitled to if their attorneys failed to do so). As a result, although defendants were entitled to present virtually unlimited mitigating evidence, many attorneys—because they lacked the training, experience, or resources—managed to present little or none on their client’s behalf.

Nearly 25 years after Gregg was decided, however, the Court took steps to remedy this problem. Thus, in Williams v. Taylor (2000), it reversed a death sentence because a capital defense attorney had failed to investigate, assemble, and present important and available mitigating evidence in a death penalty case. Specifically, the Court found that the defense attorney had rendered “ineffective assistance of counsel” because he had failed to “conduct a thorough investigation of the defendant’s background.” As a result, he did not uncover and introduce potentially important mitigating evidence at trial, including the fact that the defendant had endured a “nightmarish childhood,” had been raised by criminally negligent and physically abusive alcoholic parents, had been committed to an abusive foster home, and was borderline mentally retarded. The trial attorney also failed to introduce available evidence about the defendant’s positive prison adjustment, including his prior good behavior in prison and extremely low violence potential in structured institutional settings.

In several subsequent decisions, the Court reaffirmed the constitutional mandate that capital attorneys must diligently pursue and present available mitigation on behalf of their clients. In perhaps the most important of these cases, Wiggins v. Smith (2003), the Court indicated that defense attorneys must investigate, analyze, and, where appropriate, present mitigating social history evidence. Wiggins emphasized that evidence of a seriously troubled background is highly relevant to what has been called “the assessment of a defendant’s moral culpability” and acknowledged that when juries are confronted with such evidence, they are likely to return a sentence less than death. The Court concluded that the American Bar Association Guidelines (2003) for competent representation in capital cases help establish “prevailing professional norms,” thereby making it incumbent on defense attorneys to investigate, analyze, and consider presenting “all reasonably available mitigating evidence,” including the defendant’s “medical and educational history, employment and training history, family and social history, prior adult and juvenile correctional experience, and religious and cultural influences.”

Psychological Underpinning of Capital Mitigation

The doctrine of mitigation is decidedly not a doctrine of legal excuse. It allows jurors to acknowledge defendants’ legal responsibility for their actions and to punish them for those actions. However, in a capital context, it provides a justification for imposing a punishment other than death. The underlying psychological rationale for this has several separate components. First, many mitigating factors that are introduced into a capital-sentencing trial serve to reduce defendants’ level of moral culpability for the crime(s) they have been found responsible for committing. That is, exposure to traumatic, deprived, or otherwise criminogenic background factors may help account for a defendant’s criminality, making him or her less personally blameworthy than otherwise. Similarly, a defendant whose behavior is significantly affected by mental health problems, cognitive or neurological impairments, or other maladies may be seen as less culpable than others not similarly afflicted. In a capital trial, depending on the nature and amount of those criminogenic forces or impairments, the defendant’s moral culpability may be reduced, so that the jury decides that a death sentence is not warranted.

Humanizing testimony and evidence that illustrates the defendant’s positive qualities and prior good acts are mitigating in a different way. This kind of capital mitigation speaks to the complexity of human nature, the fact that a life can be judged on the basis of more than the worst thing(s) someone has done, and encourages jurors to reflect comprehensively on the value of the life they are being called on to take. Mitigation about future adjustment, potential contributions to prison life, and the defendant’s connections and importance to family and loved ones speaks to the psychological and social cost of a death verdict and encourages jurors to weigh these factors in the sentencing equation they employ.


  1. American Bar Association. (2003). Guidelines for the appointment and performance of defense counsel in death penalty cases. Hofstra Law Review, 31, 913-1090.
  2. American Law Institute. (1962). Model penal code. Philadelphia, PA: Author.
  3. Fabian, J. (2003). Death penalty mitigation and the role of the forensic psychologist. Law &Psychology Review, 27, 73-120.
  4. Furman v. Georgia, 408 U.S. 238 (1972).
  5. Goodpaster, G. (1983). The trial for life: Effective assistance of counsel in death penalty cases. New York University Law Review, 58, 299-362.
  6. Gregg v. Georgia, 428 U.S. 153 (1976).
  7. Haney, C. (1995). The social context of capital murder: Social histories and the logic of capital mitigation. Santa Clara Law Review, 35, 547-609.
  8. Haney, C. (2005). Death by design: Capital punishment as a social psychological system. New York: Oxford University Press.
  9. Lockett v. Ohio, 438 U.S. 586 (1978).
  10. Miranda v. Arizona, 384 U.S. 436 (1966).
  11. Note, Eighth Amendment—Death penalty: Weighing of aggravating and mitigating factors. (2006). Harvard Law Review, 120, 144-154.
  12. Wiggins v. Smith, 539 U.S. 510 (2003).
  13. Williams v. Taylor, 529 U.S. 362 (2000).

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