The reasonable person standard is key to both Criminal Law and Torts. What does and does not count as reasonable behavior and decision-making is frequently deter- mined by lay jurors. Hence, laypeople’s understanding of the term must be considered, especially whether they use it predominately in an evaluative fashion. In this corpus study based on supervised machine learning models, we investigate whether laypeople use the expression “reasonable” mainly as a descriptive, an evaluative, or merely a value-associated term. We find that “reasonable” is predicted to be an evaluative term in the majority of cases. This supports prescriptive accounts, and challenges descriptive and hybrid accounts of the term – at least given the way we operationalize the latter. Interestingly, other expressions often used interchangeably in jury instructions (e.g. “careful,” “ordinary,” “prudent,” etc.), however, are predicted to be descriptive. This indicates a discrepancy between the intended use of the term “reasonable” and the understanding lay jurors might bring into the courtroom.

The COVID-19 pandemic has made health law and disability law prominent in every area of life. Health law and disability law were therefore upgraded to the status of popular law school classes as well as to more mainstream legal scholars’ research agendas. Experimental jurisprudence scholarship has also gained momentum in recent years. Yet while the use of experiments to study policy and legal issues related to health and disability is off to a promising start, the potential of this approach remains far from being realized. In this essay, I will first show how the use of experiments has helped revisit core concepts in the fields of health law and disability law. I then review three strands of work that emerged in the existing literature on “experimental health and disability law”: the study of framing – the language of public health messaging; measuring perceived deservingness of government benefits; and testing efficacy of physicians’ conflict of interest disclosures. I conclude by pointing to new directions scholars should explore in future work.

The last several years have featured the development of legal longtermism – the set of theories associated with the view that law should be concerned with ensuring the long-term future goes well. Although recent literature has shown that the principles underlying legal longtermism are widely endorsed across the Anglosphere, it remains an open question whether these principles are endorsed across cultures. Here we surveyed laypeople (n=2,938) from ten countries – Australia, Canada, Chile, Japan, Mexico, South Africa, South Korea, Spain, United Kingdom and United States – regarding law’s role in protecting future generations. We find participants in our sample widely endorse (a) increasing legal protection for future humans beyond current levels; (b) extending personhood and standing to some subset of humans living in the near and far future; and (c) prioritizing the interests of future people over those of present people in some national and international lawmaking scenarios. Taken together, these results suggest the notion of granting rights and legal protection to future generations is endorsed cross-culturally, carrying wide-ranging implications for legal theory, doctrine, and policy.

Recent empirical work demonstrates that some instances of material deception are perceived by ordinary people as consent-defeating, whereas other instances are not. One hypothesized account of these divergent lay intuitions draws on the notion of “essence”: Roughly speaking, lies that pertain to the “core” or “nature” of a consented-to act are perceived as precluding consent, whereas lies that pertain to features that are “nonessential” or “collateral” to the act are perceived as compatible with consent. To assess this hypothesized account, an independent measure of “essence” – one that does not rely with problematic circularity on notions of consent – is needed. This chapter draws on an emerging cognitive science literature that deploys linguistic probes to investigate how people intuitively represent human action. Here, we will consider two such probes, the “by” test and the “basically doing” test, and observe that whereas the former predicts judgments of consent, the latter does not.

Should judges and other legal decision-makers follow the literal meaning of applicable legal rules even if there are compelling reasons to do otherwise? The question of the primacy of plain meaning in legal interpretation is one of the oldest and most persistent problems in the philosophy of law. In this chapter, we argue that new arguments are available in this debate, emerging from recent developments in experimental jurisprudence. We posit that legal interpretation is, to some extent, an exercise in coordination: Judges seek to interpret rules in a way that would match interpretations of their peers, of other legal officials, and of society at large. In such a strategic context, the plain meaning of law often constitutes a focal point around which different legal actors can coordinate – allowing them to promote the uniformity and predictability of law and, ultimately, to sustain the rule of law.

Kneer and Bourgeois-Gironde (2017) reported that legal experts’ intentionality ascriptions are susceptible to the “severity effect” (i.e., influenced by differently harmful side effects), which violates the outcome-independent legal concept of intentionality prevalent in many criminal law systems. This challenges the “legal expertise defense” (= legal experts are more competent users of legal concepts and their legal judgments are more reliable than those of laypeople). Prochownik, Krebs, Wiegmann, and Horvath (2020) hypothesized that the “severity effect” might be due to confounding features of the previously used vignettes (i.e., the somewhat bad cases not being perceived as harmful by legal experts). They created new stimuli with clear cases of harm that differed in the degree of harm across two conditions, and they did not observe any “severity effect” in legal experts or laypeople. Yet, the difference in harm ratings across conditions was not very large. The current study addresses this limitation: Even after increasing the difference in the perceived degree of harm, we still do not observe the “severity effect” in legal experts or laypeople.

Legal research is a repeat offender – in the best sense of the term – when it comes to making use of empirical and experimental methods borrowed from other disciplines. We anticipate that the field’s response to developments in eye-tracking research will be no different. Our aim is to aid legal researchers in the uptake of eye-tracking as a method to address questions related to cognitive processes involved in matters of law abidance, legal intervention, and the generation of new legal rules. We discuss methodological challenges of empirically studying thinking and reasoning as the mechanisms underlying behavior and introduce eye-tracking as our method of choice for obtaining high-resolution traces of visual attention. We delineate advantages and challenges of this methodological approach, and outline which concepts legal researchers can hope to measure with a toy example. We conclude by outlining some of the various research avenues in legal research for which we predict a benefit from adopting eye-tracking to their methodological toolbox.

In the common law tradition, legal decisions are supposed to be grounded in both statute and precedent, with legal training guiding practitioners on the most important and relevant touchstones. But actors in the legal system are also human, with the failings and foibles seen throughout society. This may lead them to take methodological shortcuts, even to relying on unknown internet users for determinations of a legal source’s relevance. In this chapter, we investigate the influence on legal judgments of a pervasive, but unauthoritative source of legal knowledge: Wikipedia. Using the first randomized field experiment ever undertaken in this area – the gold standard for identifying causal effects – we show that Wikipedia shapes judicial behavior. Wikipedia articles on decided cases, written by law students, guide both the decisions that judges cite as precedents and the textual content of their written opinions. Collectively, our study provides clear empirical evidence of a new form of influence on judges’ application of the law – easily accessible, user-generated online content.

This chapter offers a critique of experimental jurisprudence. While experimental jurisprudence can make an important contribution to legal knowledge and legal theory, theorists and practitioners of experimental jurisprudence should also be aware of its limitations. Experimental jurisprudence cannot, by itself, resolve legal theoretical debates. It is just one limited tool, with an important but partial role to play in the collective project of understanding and evaluating law and legal rules, institutions, and practices. This chapter offers a summary survey of some of the limitations of experimental jurisprudence in special and general jurisprudence. It also argues that, if we want to fully understand law and legal concepts, practices, and institutions, experimental jurisprudence needs to be supplemented with other perspectives – such as those provided by anthropology, qualitative research, and the humanities. These perspectives can capture precisely what experimental jurisprudence must necessarily ignore: that law is a complex institutionalized social and cultural practice constituted by the thought and talk of legal experts.

The US Supreme Court routinely purports to resolve statutory interpretation disputes by deferring to the enactment-era “ordinary,” “public” meaning of the statute’s terms (their “OPM”). In recent years, scholars have begun using surveys and experiments to test judges’ claims about OPM in particular cases, and to critique modern textualist theory and practice more generally. This chapter argues that surveys and experiments can provide highly probative evidence of OPM, whether one favors the more populist conception of OPM on which the modern Supreme Court frequently purports to rely, or the more thoroughly stylized conception that some scholars favor. Drawing on the handful of published survey-experimental efforts to date, and responding to scholarly criticisms of them, the chapter suggests that surveys and experiments may prove too probative for comfort. If modern textualists were to spell out ex ante their conception of OPM with sufficient precision to render it capable, even in theory, of resolving the hard cases they claim it resolves, then survey-experimental data might reveal that the theory produces disappointing results – not just in discrete cases, but across the board.

Psychology and law, by their nature, are deeply entwined. Both are about human behavior – understanding it, modifying it, regulating it. Psychology’s research engagement with legal topics enjoys a long history, but until recently has been largely limited to clinical assessment (e.g., capacity, insanity) and police and trial evidence and procedures (e.g., eyewitnesses, jury instructions). The traditional canon of “Psychology & Law” research gained prominence when DNA evidence revealed that many wrongful convictions involved problems foreseen by psychologists. Also, the emergence of “Behavioral Law & Economics” likely provided more legitimacy to law’s engagement with empirical psychology topics and methods, spurring “Law & Psychology” teaching and research in law schools. The expanded range of research can be found across the US law curriculum as illustrated in four main first-year courses – Criminal Law, Torts, Contracts, and Property – and two commonly taken or required courses – Evidence and Professional Responsibility. The current experimental jurisprudence boom has added to the topics and methods used in this research and amplifies the existing trend in which psychology engages more closely with the content and values of law.

The present chapter presents an overview of the recent applications of experimental methods to jurisprudential issues in international law as well as potential future developments of the field. We discuss how experimental methods can helpfully contribute to the understanding of the different moments of international law: the making of new rules, the interpretation of these rules, and, finally, their application in practice. We also present three main topics that constitute the studies of rule application in practice, namely, the mechanisms behind human judgment, policymaking, and, finally, the decision taking itself. We identify some future potential lines of development based on the example of the current disagreements over the definition of an international crime of “ecocide” and discuss some potential limitations of the experimental approach.

Experimental jurisprudence draws methods and theories from an increasingly wide variety of fields, including psychology, economics, philosophy, and political science. However, researchers interested in legal thought have thus far paid relatively little attention to its origins in development. This chapter highlights an emerging approach that leverages methods and insights from developmental science to better understand the nature and development of adult intuitions about the law. By studying children’s earliest intuitions about rules, laws, and other topics, this “intuitive jurisprudence” approach can provide new methods and theoretical frameworks for experimental jurisprudence, as well as clarify places in which the law does or does not match human intuitions about justice. Already, developmental psychology and legal scholarship may converge to be mutually informative in a number of diverse areas, and this chapter reviews several, including: intent and punishment; fairness and procedural justice; ownership and property rights; trust in testimony and evidentiary issues; and social biases and equal protection under the law.

Legal language is often ambiguous. Consider: “Only cars and trucks with permits are allowed.” Does [PP with permits] have “wide scope” over the entire series [NP cars and trucks] or “narrow scope” over only the closest noun, [trucks]? Judges often choose narrow scope, citing a legal canon, the “Last Antecedent Rule.” But they sometimes choose wide scope, referencing the “Series Qualifier Canon,” which assigns modifiers to a series. Though judges claim to want to use “most people’s” interpretations, these conflicting choices led us to ask “What WOULD most people say?” We ran three experiments to find out.

Overall, wide scope was preferred. With biased PPs, the preference dropped slightly when the bias matched the last noun, “[NP cars and trucks] [PP with trailers],” but not the first, “[NP trucks and cars] [PP with trailers],” where a universal syntactic “No Crossing Branches principle” limits the PP’s domain. With temporal PPs, “People may park [NP cars and trucks] [PP on weekends],” the preference was also uniformly wide scope, not surprisingly, since these PPs can only modify verbs, not nouns. Taken together, our experiments show how experimental psycholinguistics can offer powerful evidence about how “most people” understand legal language, important information for judges and lawmakers alike.

Rules are ubiquitous. They figure prominently in all kinds of practical reasoning. Rules are especially important in jurisprudence, occupying a central role in answers to the question of “what is law?” In this chapter, we start by reviewing the evidence showing that both textual and extratextual elements exert influence over rule violation judgments (Section II). Most studies about rules contrast text with an extratextual element identified as the “purpose” or “spirit” of the rule. But what counts as the purpose or the spirit of a rule? Is it the goal intended by the rule maker? Or is purpose necessarily moral? Section III reviews the results of experiments designed to answer these questions. These studies show that the extratextual element that’s relevant for the folk concept of rule is moral in nature. Section IV turns to the different explanations that have been entertained in the literature for the pattern of results described in Sections II and III. Finally, in Section V we discuss some other extratextual elements that have been investigated in the literature. We conclude with a brief discussion of future directions.

As a branch of analytic philosophy, jurisprudence, understood as legal philosophy, is often thought to be a nonempirical enterprise. It turns out, however, that unresearched, unsupported, and largely impressionistic empirical assertions have long been a part of the analytic jurisprudential enterprise. Recognizing this is the first step towards examining and testing these empirical assertions. Using the proclivity of ordinary people to obey the law (or not) because of the content-independent existence of law as one example of such an assertion, this chapter explores how that assumption might be tested by experimental and other means, as a prolegomenon to testing the empirical claims and assumptions that have long pervaded even the most traditional jurisprudence.

Legal concepts can sometimes be unclear, leading to disagreements concerning their contents and inconsistencies in their application. At other times, the legal application of a concept can be entirely clear, sharp, and free of confusions, yet conflict with the ways in which ordinary people or other relevant stakeholders think about the concept. The aim of this chapter is to investigate the role of experimental jurisprudence in articulating and, ultimately, dealing with competing conceptual inferences either within a specific domain (e.g., legal practice) or between, for example, ordinary people and legal practitioners. Although this chapter affirms the widespread assumption that experimental jurisprudence cannot, in and of itself, tell us which concepts should be applied at law, it highlights some of the contributions that experimental jurisprudence can, in principle, make to normative projects that seek to prescribe, reform, or otherwise engineer legal concepts. Thus, there is more that experimental jurisprudence can normatively offer than has usually been claimed.