Dateline: January, 2007, Issue 6
Frequently, jurors are asked to vote for manslaughter rather than murder due to a defendant's emotions overcoming the defendant's reason at the time of a killing.
Spackman et al. (2002) examined factors jurors take into consideration when determining whether a defendant's emotions serve as mitigating circumstances to reduce a murder charge to a verdict of manslaughter.
These researchers found four factors were important in predicting jurors' murder/manslaughter verdicts:
(1) The defendant's history of violence with the victim. A defendant having a history of frequent and intense arguments and/or violence with the victim is more likely to be convicted of murder. Unexpected events, or a defendant and victim having mutual respect for each other, increase chances of a manslaughter verdict.
(2) The degree to which the defendant's actions are perceived as unintentional. Intentional actions are more likely to result in murder convictions. Defendants who pull out a gun they always carry "without even thinking" are more likely to be convicted of manslaughter.
(3) The degree to which a defendant dwells on or purposely attends to his or her emotions. Defendants dwelling on their emotions and allowing them to intensify are more likely to receive a murder conviction. When defendants become overwhelmed and "just snap," or when they did not intend to feel as they did (when the emotion just "washes over them"), they are more likely to be convicted of manslaughter.
(4) The particular emotion experienced by the defendant. Among jealousy, anger, sadness and fear, a defendant who was motivated by jealousy has the greatest likelihood of a murder conviction, and a defendant feeling fear the least; anger is slightly more likely to result in a murder conviction than sadness.
For jurors, no prior history of violence, not thinking, and being overcome with fear point to manslaughter, and a prior history of violence, feeling jealous, and dwelling on that feeling point to murder.
Source Spackman, M. P., Belcher, J. C., & Hansen, A. S. (2002). Effects of emotional intensity on mock jurors' murder/manslaughter distinctions. Journal of Applied Biobehavioral Research, 7, pp. 87-113.