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The Influence of Intuition on Legal Decision-Making

There is a surprising correspondence between the law and laypeople’s intuitive judgments. This is the bottom line of a recently published article in Law and Human Behavior. Below is a summary of the research and findings as well as a translation of this research into practice.

Featured Article | Law and Human Behavior | 2016, Vol. 40, No. 6, 707-720

Wrong or Merely Prohibited: Special Treatment of Strict Liability in Intuitive Moral Judgment


Carly Giffin University of California, Berkeley
Tania Lombro University of California, Berkeley


Most crimes in America require that the defendant have mens rea, Latin for “guilty mind.” However, mens rea is not legally required for strict liability crimes, such as speeding, for which someone is guilty even if ignorant or deceived about her speed. In 3 experiments involving participants responding to descriptive vignettes, we investigated whether the division of strict liability crimes in the law reflects an aspect of laypeople’s intuitive moral cognition. Experiment 1 (N _ 396; 236 male, 159 female, 1 other; Mage _ 30) found evidence that it does: ignorance and deception were less mitigating for strict liability crimes than for “mens rea” crimes. Experiments 2 (N _ 413; 257 male, 154 female, 2 other; Mage _ 31) and 3 (N _ 404; 183 male, 221 female, Mage _ 35) revealed that strict liability crimes are not treated as pure moral violations, but additionally as violations of convention. We found that for strict liability crimes, ratings of moral wrongness and punishment were influenced to a greater extent by the fact that a rule had been violated, even when harm was kept constant, mirroring the legal distinction of malum prohibitum (wrong as prohibited) versus malum in se (wrong in itself). Further, we found that rules prohibiting strict liability crimes were judged more arbitrary than corresponding rules for “mens rea” crimes, and that this judgment was related to the role of mental states. Jointly, the findings suggest a surprising correspondence between the law and laypeople’s intuitive judgments.


rule violation, knowledge, decision making, explanations, law

Summary of the Research

“The first requirement of a sound body of law,” wrote Justice Oliver Wendall Holmes, “is that it should correspond with the actual feelings and demands of the community, whether right or wrong.” Whether one believes that the law should conform to the feelings of the community, or vice versa, the idea of a correspondence between the legal system and laypeople’s intuitive judgments continues to have popular and academic support. To the extent this correspondence holds, the psychology of moral judgment has important implications for the law, and the law provides a rich source of information about human moral psychology” (p. 707).

“One important correspondence between the law and intuitive judgments can be seen in the legal system’s requirements regarding intent. Characteristically, a person cannot be found guilty of a crime in America unless that person had some intent to commit the crime or acted in a way that was negligent or reckless. Legally, this concept is referred to as “mens rea,” Latin for “guilty mind,” and has been a part of criminal law for centuries. Psychological research confirms that, in most cases, a person’s intent is seen as a crucial variable in assigning moral responsibility and punishment” (p. 707).

“Notably, the law makes an exception concerning the role of mens rea for a specific class of crimes known as ‘strict liability’ crimes. In criminal law, strict liability crimes are crimes for which the prosecution does not have to prove that the defendant had the requisite mens rea with respect to at least one element of a crime, and, in many cases, the defendant is not allowed to present evidence that she made a reasonable mistake or lacked relevant knowledge or intent” (p. 707).

“In the present work, we investigate whether the legal distinction between strict liability crimes and mens rea crimes reflects a psychological distinction as well. One possibility is that strict liability crimes represent a departure from a general correspondence between the law and intuitive judgments. Indeed, many scholars point out how unintuitive the imposition of strict liability can seem. But a second possibility is that the distinction between strict liability and mens rea crimes reflects a psychological distinction that has not been adequately recognized within the psychological literature. Based on our findings, this is what we will ultimately suggest” (p. 708).

Three experiments were conducted to investigate if the legal disparity between strict liability and mens rea crimes is reflective of innate moral decision-making. “Experiment 1 revealed that judgments concerning mens rea crimes were in fact more sensitive to the actor’s knowledge and intent than were those concerning strict liability crimes. When an actor transgressed knowingly, punishment and censure were greater for mens rea crimes than for strict liability crimes, but when the actor transgressed without knowledge and intent (whether merely ignorant or deceived), this pattern was reversed. As a result, judgments for mens rea crimes were strongly influenced by the actor’s knowledge and intent, whereas those for strict liability crimes were about the same. Put differently, ignorance was treated as a mitigating factor for mens rea crimes, but not for strict liability crimes” (p. 716).

“In Experiments 2 and 3, we found support for a possible explanation: that strict liability crimes have more features that are malum prohibitum, or wrong because prohibited, while mens rea crimes are largely malum in se, or wrong in themselves. Experiment 2 found that judgments for strict liability crime were more dependent on the presence of a rule: when a statute was revoked, ratings for moral censure and punishment decreased more for strict liability crime than for mens rea crimes. These findings have analogues in social and cognitive development, where research differentiates between moral and “conventional” wrongdoing. Experiment 3 focused on another aspect of conventionality: the potentially arbitrary nature of the rule involved. We found that rules prohibiting strict liability crimes were on average judged more arbitrary than rules for mens rea crimes, and that the more arbitrary the rule, the more attenuated the role of mental states” (p. 716).

“In sum, our studies are the first (to our knowledge) to relate the strict liability designation to laypeople’s intuitive moral judgments. We find that strict liability and mens rea crimes differ in two potentially related ways: mens rea crimes are more sensitive to the presence or absence of relevant knowledge, but strict liability crimes are more contingent on the presence of a rule. Our studies suggest that people find strict liability crimes to be more arbitrary and malum prohibitum, while mens rea crimes appear to be, to a greater extent, malum in se. This is good news for those, like Justice Holmes, who believe that the law should reflect community standards, but it may still be troubling for those who believe the law should maintain the highest standard of justice, even when the community does not demand it” (p. 718).

Translating Research into Practice

“Finding that the legal category of strict liability mirrors a cognitive distinction is exciting, but also potentially surprising: some of strict liability’s most vocal criticism is rooted in the belief that defendants’ mental states should and would have an effect on their legal outcomes. That is, there is often an implicit assumption that jurors care about a defendant’s knowledge or intent, and that presenting evidence for the absence of either would mitigate a defendant’s penalty in strict liability cases” (p. 717).

“In contrast, we found that our participants’ judgments were surprisingly consistent with the law, finding mental states less relevant for strict liability crimes than for other crimes. We are not arguing that mental states play no role for strict liability crimes, but our results do suggest that the (putative) counter intuitiveness of this aspect of strict liability has been overstated, and might not be the most compelling basis for arguments by its opponents. Indeed, recent work in the realm of torts has found that laypeople may endorse strict liability more strongly than scholars” (p. 717).

“Our studies also bear on more general questions about the role of explanations in legal judgment. We found evidence that offering an explanation for an actor’s mental states can be more mitigating than the mere absence of knowledge. Specifically, Experiments 1 and S1 found that participants in the unspecified condition gave significantly higher ratings on every dependent measure than participants in either of the conditions that offered explanations for false beliefs: unknowing or deceived. Experiment S1 also found that deception was more mitigating than bad information. Our studies thus go beyond prior work about the importance of knowledge and intent by showing that while mental states are undeniably important, explanations for those mental states are as well” (p. 717).

Other Interesting Tidbits for Researchers and Clinicians

“Our results support the idea that the relative arbitrariness of a crime, and therefore its status as malum prohibitum, is intuitively recognized and influences judgments. However, open questions remain concerning how participants were interpreting and evaluating arbitrariness. In addition, the relationship between arbitrariness and the role of mental states was significant, but small. This suggests that a variety of additional factors influence the relative importance of mental states in legal judgment, and identifying these factors is an important direction for future research” (p. 717).

“Another concern is the number of participants who failed our attention check questions. Using an Internet sample necessitates stringent attention checks, as participants cannot be monitored as they would be in a lab. Despite our multiple checks, however, our exclusion rates were comparable to those for other studies run on Mechanical Turk. One advantage of using a Mechanical Turk sample is that it is more representative of a jury than a sample of university undergraduates. That said, extending this line of research to jury eligible participants who engage in deliberation over more detailed and realistic cases has clear value” (p. 717).

Join the Discussion

As always, please join the discussion below if you have thoughts or comments to add!

Authored by Amanda Beltrani

Amanda Beltrani is a current graduate student in the Forensic Psychology Masters program at John Jay College of Criminal Justice in New York. Her professional interests include forensic assessments, specifically, criminal matter evaluations. Amanda plans to continue her studies in a doctoral program after completion of her Masters degree.

One thought on “The Influence of Intuition on Legal Decision-Making

  1. As I am not used to legal terms, I did get overwhelmed in part of this. But, To me it does matter whether someone knew what they were doing was wrong and hurtful vs someone who errors without having mal intent. I feel that malintent does effect people more powerfully,
    because to act on those thoughts is a deliberate, violent assault on another, much much harder to forgive.

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