The Psychology and Law of Voluntary Manslaughter: What Can Psychology Research Teach Us About the 'Heat of Passion' Defense?

The doctrine of voluntary manslaughter mitigates a defendant's crime and punishment when the defendant kills in the “heat of passion” generated by an extremely provoking event, such as witnessing a spouse's adultery. The doctrine relies on empirical assumptions about the effects of emotion, especially anger, on decision-making, and about the time course of emotion. Modern psychology research questions at least some of these assumptions, but the law adheres to its traditional approach. The law's resistance to change may stem partly from its dependency on language and analogic reasoning; the words we use to describe emotions like anger, revenge, and fear may shape people's perceptions concerning these emotions and thus may constrain the law's ability to respond to new psychological insights about emotion. At the same time, the law must serve normative goals that transcend the quest for empirical knowledge. For this reason and others, psychology can only inform the law, but cannot force changes in the law. Copyright © 2007 John Wiley & Sons, Ltd.