In 1993, James Erin McKinney was convicted in an Arizona court of committing two robberies and murders over the course of 13 days. McKinney was convicted by a jury of first-degree murder and faced a possible death sentence.
At the capital sentencing hearing, the judge was asked to determine the appropriate sentence—death or life imprisonment—by weighing aggravating and mitigating factors that would favor a death (greater) or life (lesser) sentence.
During the hearing, a psychologist testified that McKinney suffered from post-traumatic stress disorder (PTSD)—a potential mitigating factor—due to a “horrific childhood” that included early substance use and multiple attempts to leave home, as well as a stint in a juvenile detention facility.
Yet when considering a potential death sentence, Arizona law permitted the judge to consider only nonstatutory mitigating factors that were “causally related to the commission of the crime.” As a result, the judge did not consider McKinney’s childhood and PTSD as mitigating factors because these issues occurred before the crime in question. The judge ultimately sentenced McKinney to death.
In December, the U.S. Supreme Court heard oral arguments to decide whether the judge should have been allowed to consider this mitigating evidence at trial.
Many states do have mitigation statutes that include a “catch-all” element that allows the defense to use any mitigating evidence they believe will lessen the likelihood of a potential death sentence. But how such mitigating evidence is used by defense attorneys and perceived by judges and jurors is less clear. Fortunately, psychological research has shed some light on this issue.
Some aspects of a defendant’s background, such as an impoverished childhood—as in the McKinney case—seem intuitively mitigating. Yet a 2010 study by Margaret Stevenson, PhD, and colleagues examined the effect of childhood abuse on jurors’ discussions in capital cases, and found that that was not always true. Instead, “jurors were more likely to argue that child abuse (and alcohol abuse) should not be used as mitigators, or to even use them against the defendant as aggravators, than they were to use them as mitigators” (Psychology, Public Policy, and Law, Vol. 16, No. 1, 2010opens in new window).
Thus, what may appear on its face to be a mitigating circumstance, such as being a victim of child abuse or being under the influence of alcohol at the time of the crime, may not be mitigating at all. And perhaps more important, this study and other studies like it have found that whether a factor is mitigating likely depends upon the individual characteristics of the decision-makers as well as how the specific mitigating circumstance interacts with other case facts, or other aggravating and mitigating circumstances.
There are a few take-home points from this discussion. The first is that defense attorneys should use caution when assuming that a factor is actually mitigating to judges and jurors. The second is that this research also reminds us to consider the interactive effects between mitigating circumstances and other case evidence. As a potential mitigating factor may be mitigating in some cases but not others, it is important to consider such evidence in the broader context of other dispositional and case factors.
