We investigated the role of moral disengagement in a legally‐relevant judgment in this theoretically‐driven empirical analysis. Moral disengagement is a social‐cognitive phenomenon through which people reason their way toward harming others, presenting a useful framework for investigating legal judgments that often result in harming individuals for the good of society. We tested the role of moral disengagement in forensic psychologists’ willingness to conduct the most ethically questionable clinical task in the criminal justice system: competence for execution evaluations. Our hypothesis that moral disengagement would function as mediator of participants’ existing attitudes and their judgments—a theoretical “bridge” between attitudes and judgments—was robustly supported. Moral disengagement was key to understanding how psychologists decide to engage in competence for execution evaluations. We describe in detail the moral disengagement measure we used, including exploratory and confirmatory factor analyses across two separate samples. The four‐factor measure accounted for a total of 52.18 percent of the variance in the sample of forensic psychologists, and the model adequately fit the data in the entirely different sample of jurors in a confirmatory factor analysis. Despite the psychometric strengths of this moral disengagement measure, we describe the pros and cons of existing measures of moral disengagement. We outline future directions for moral disengagement research, especially in legal contexts.