Evaluation of Aggravating and Mitigating Circumstances in Capital Cases

If a defendant is found guilty of a capital crime, the triers of fact are called on to weigh the significance of the aggravating and mitigating factors of the case and to use such judgments to decide whether the defendant will receive the death penalty or a life sentence. During the sentencing phase, the prosecution presents the relevant aggravating factors of the case, while the defense is charged with the duty of providing mitigation factors. Although no standard model exists to offer procedures for the investigation of mitigating factors, scholars, clinicians, and researchers have offered recommendations concerning the common types of information needed and the appropriate ways to present it to the jury. In all cases, a mitigation evaluation is conducted with the goal of humanizing the defendant to the jury, in the hope that they will not recommend the death penalty.

During the penalty phase of a capital offense trial, the triers of fact (i.e., the judge or jury depending on the state) are presented with two types of information: (1) aggravating factors (i.e., facts from the case that make it especially serious or heinous) and (2) mitigating factors (i.e., facts from the case that may reduce the defendant’s moral culpability). As set forth in Ring v. Arizona (2002), to come forward with a recommendation for death, the jury must first be convinced beyond a reasonable doubt that the state has met its burden of proof with respect to the presence of one or more aggravating factors. Once this has been done, the defense is required to present mitigating factors with the goal of convincing the trier of fact that this individual does not deserve the penalty of death. The driving force behind this practice is the U.S. Supreme Court’s assertion in Furman v. Georgia (1972) that sentences in capital cases should be individualized and should not be disproportionate or inappropriate given the mitigating factors in the case.

Aggravating factors in a capital case are often readily apparent from the circumstances of the crime. Like other states, the state of Texas has statutory aggravating factors that are precisely defined. Three examples of the criteria set forth by the Texas Penal Code are (a) if the person murders more than one person during the same criminal transaction; (b) if the person murders an individual under 6 years of age; and (c) if the person intentionally commits a murder in the course of committing (or attempting to commit) kidnapping, burglary, robbery, aggravated sexual assault, arson, or obstruction or retaliation.

In contrast to aggravating factors, which are established by statute, mitigating factors can be anything the defense chooses to present that it believes may sway the trier of fact to determine that life without parole is the proper and just sentence in the particular case. The following list provides just a few examples of the most common mitigating factors that are brought forward in a capital trial: history of neglect and/or abuse during the formative years, the presence of a mental illness, youthfulness, and a limited history of involvement with the legal system. It was in Lockett v. Ohio (1978) that the U.S. Supreme Court decided that limiting the type and amount of mitigating factors that can be presented to the trier of fact is unconstitutional.

When deciding the sentence for a defendant who has been found guilty, jurors are asked to weigh the aggravating circumstances against the mitigating circumstances of the case. Each state has its own laws regarding how jurors are instructed to weigh aggravating and mitigating circumstances, but in all states, each individual juror must weigh the circumstances and decide whether the defendant is sentenced to death or life in prison. In many states, the death penalty can be imposed only if the jury returns a unanimous decision.

With respect to the process of conducting a mitigation evaluation, the onus is on the defense team to conduct a thorough investigation of all possible mitigating factors. To complete such an investigation, it is recommended that the defense team hire one or more professionals to carry out the various tasks required for the investigation and presentation of mitigating circumstances. In Wiggins v. Smith (2003), the U.S. Supreme Court ruled that failure on the part of the defense team to properly investigate and introduce mitigating evidence can result in a finding of ineffective assistance of counsel, leaving open the possibility that the verdict will be overturned on appeal.

Perhaps the most traditional form of investigation is that carried out by a professional known as a mitigation specialist. Although social workers often serve in this role, other professionals, such as paralegals, legal researchers, and attorneys, also work in this capacity. Regardless of the profession, the role of the mitigation specialist requires a commitment to uncover all possible mitigating factors, and to do this, it is imperative that he or she has a wide repertoire of knowledge and skills. For example, it is expected that the specialist be well versed in the field of human development and be skilled in the areas of data collection, interviewing, and putting together a person’s life history. At a minimum, the mitigation specialist should request and receive records that are reflective of the defendant’s life history (e.g., medical records, mental health records, and school records), conduct interviews with a variety of individuals who are familiar with the defendant (e.g., parents, siblings, friends, employers, teachers, therapists), and conduct multiple interviews with the defendant. In many cases, it is also critical that the mitigation specialist investigate the life histories of the defendant’s parents and other members of their immediate and extended family. Such information is important with respect to being able to evaluate both genetic and environmental influences on the defendant’s development. Given the breadth of the investigation required, it is recommended that it be initiated long before the trial is set to begin.

The goal of the mitigation specialist is to compile information concerning the defendant’s life history that will offer insight into how the defendant’s life experiences have shaped his or her development. Presentation of such information is aimed at humanizing the individual to the degree that the trier of fact recommends a life sentence. It should be clear, however, that the goal of mitigation is not to excuse the defendant’s behavior but instead to explain how an individual can become the type of person who could be in a position to commit a capital offense.

Depending on their credentials and the role that they have been asked to play, mitigation specialists may or may not testify as to the information gathered. In cases where they do not testify, the information they gather is provided to one or more appropriate professionals. These individuals not only will present the information to the court but also will be expected to present it in such a way that it is accessible to the jury. For example, a psychologist or a social worker may testify about the defendant’s childhood development, the impact of childhood abuse, the impact of being raised without a father figure in the home, and any mental illness he or she may have experienced. A neuropsychologist may provide expert opinions regarding the influence of traumatic brain injury on the defendant’s functioning, and an anthropologist or sociologist may testify to the effects of sociological or economic factors related to the defendant’s neighborhood that may have influenced the defendant’s developmental trajectory.

Regardless of who presents the mitigation information to the court, recent literature has recommended that the presentation of such information be structured on the concepts of risk factors, protective factors, and resiliency. In brief, risk factors can be described as events in an individual’s life that have been scientifically linked to negative outcomes in functioning. Examples of common risk factors in capital defendants include childhood or adult trauma, childhood abuse or neglect, poverty, substance abuse, negative peer groups, cognitive impairment, and a diagnosis of conduct disorder in childhood or adolescence. Research has shown that individuals who have experienced multiple risk factors during their development are at a greater likelihood of exhibiting dysfunction in multiple domains. The individuals who are retained to testify about such risk factors have an obligation not only to deliver their findings to the court but also to illustrate how those risk factors influenced the development of this defendant.

To further the defense team’s endeavor of obtaining a non-death sentence, the mitigation expert(s) should also discuss the relevant protective factors that the defendant has experienced. Protective factors can be described as those events or experiences in the defendant’s life that may have lessened the likelihood that the defendant would have engaged in violent or dangerous behavior in the past. Examples of common protective factors include social support from family and friends, prior involvement in mental health treatments, and financial stability. It is quite typical for an expert to discuss how the absence of protective factors negatively affected the defendant’s developmental trajectory and if protective factors were present, why they did not buffer the defendant against the negative influence of the risk factors.

The final dimension of mitigation presentation should include a discussion of the defendant’s lack of resilience in the context of his or her experience with risk and protective factors. Resilience refers to the ability of individuals who have experienced great adversity to overcome such experiences and live a functional life in adulthood. Since only a small minority of individuals who face great adversity during their development actually go on to exhibit severe dysfunction in adulthood, it is important to convey to the jury how the defendant’s unique combination of risk and protective factors, along with his or her response to them, led to the violent behavior for which the defendant has been convicted.

To date, research has not found any one strategy that is successful in all cases, nor has research identified any one mitigating factor that influences juror decision making in all cases. On the contrary, it is likely that the success of mitigation relates to the quality of the inves-tigation and the presentation of information that is unique to the case. As such, it would be inappropriate for defense attorneys and other members of the defense team to think that there is a template that can be applied to these investigations. Finally, it should be noted that even the most eloquent presentation of mitigation evidence can be insufficient to counteract the effects of intrinsic juror biases, impairments in understanding the concept of aggravating and mitigating factors, and misinterpretation of instructions to the jury regarding how to weigh the evidence presented to them.

See also:

  • Aggravating and Mitigating Circumstances in Capital Trials
  • Death Penalty
  • Forms of Expert Psychological Testimony
  • Mental Illness and the Death Penalty
  • Mental Retardation and the Death Penalty


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  2. Fabian, J. M. (2003). Death penalty mitigation and the role of the forensic psychologist. Law and Psychology Review, 27, 73-120.
  3. Furman v. Georgia, 408 U.S. 238 (1972).
  4. Lockett v. Ohio, 438 U.S. 586 (1978).
  5. Miller, J. (2003). The defense team in capital cases. Hofstra Law Review, 31, 1117-1141.
  6. Ring v. Arizona, 536 U.S. 584 (2002).
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  9. Wiggins v. Smith, 539 U.S. 510 (2003).