A great deal of research in legal decision making has overlooked the influence of affect on the decision-making process. The present study measured the fluctuation of emotions across five time points of a capital trial and tested the overall relationship between changes in emotion and sentencing decisions. The results showed that across all participants, anger initially increased and then decreased during the course of a capital punishment trial. Most importantly, the more individual mock jurors' anger increased during any stage of the trial, the more likely they were to assign a death sentence. Furthermore, when jurors' anger increased, they rated mitigating factors presented by the defense as weaker and the weaker mitigation mediated the relationship between change in anger and sentencing. The paper ends with a discussion of theoretical explanations and policy implications. Copyright © 2012 John Wiley & Sons, Ltd.