A Development-Informed Concept of Adolescent Mens Rea

Mens rea is central to criminal legal systems in the United States. The accused’s state of mind not only signals culpability but drives sentencing following conviction. For their part, degrees of mens rea are divided between the subjective and objective; subjective assigns culpability based on the actor’s actual state of mind, and objective assigns culpability based on a reasonable-person standard external to the actor. To establish these mental states, a factfinder may infer a state of mind from known facts. A gun tucked into a purse may signal pre-meditation or purposefulness when it is used to kill a victim; speeding could signal recklessness; failure to feed a child may signal neglect. This process of inference requires a factfinder to consider the evidence presented and to assign meaning to that evidence based on the factfinder’s own experiences and thought processes. Although there is always a risk that the factfinder may draw the wrong inference, this risk is exaggerated for accused adolescents, whose mental processes differ from those of adult factfinders. Neuroscience reveals striking differences between adolescent and adult brains as well as significant differences in decision-making processes and perceptions of reality. Adolescents are more likely to engage in high-risk behaviour, less likely to understand long-term consequences, and more susceptible to peer pressure than their adult counterparts. This chapter identifies the significance of this neurological data to mens rea assessments of juveniles in the United States and urges a reconsideration of such assessments based not on a uniform adult standard but rather on one that accounts for adolescent brain development.