The Language of Mens Rea


This Article empirically tests two key questions. First: How sensitive are jurors to variations in the language that delineates the criminal mental state categories? Second: To what extent do jurors assign culpability in the manner assumed by the Model Penal Code (MPC)?

In prior work, we challenged numerous assumptions underlying the MPC mental state architecture, which divides guilty minds into four kinds: purposeful, knowing, reckless, and negligent. Our experiments showed that subjects had profound difficulty categorizing some of the mental states, particularly recklessness, in the context of scenarios in which hypothetical actors caused harmful results. And, when asked to punish hypothetical actors, subjects punished knowing behavior and reckless behavior indistinguishably.

Here, we extend our prior work in two main ways. First, we show that a person's ability to apply the MPC mental states is susceptible to subtle variations in the language that defines and communicates them. For instance, we demonstrate that using slightly different wording can significantly improve participants' ability to accurately identify the mental state of recklessness (notwithstanding that reckless and knowing mental states remain by far the hardest to classify). Second, we show that even when people can see the mental state distinctions that the MPC draws, they don't necessarily rank order the mental states-by culpability level-in the order the MPC assumes.

These findings raise questions about the normative basis for the knowing/reckless distinction in the MPC's mental state hierarchy in the context of result elements. Further, because even small changes in phrasing can produce significant differences in juror evaluation, the findings raise genuine concerns about the adequacy of MPC-based culpability instructions in criminal cases. Our results suggest the need for a critical reexamination of the substantial divide between the expectations and assumptions of drafters of criminal codes, on one hand, and empirical reality, on the other.

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