This chapter contains section titled: Scope of the Topic A Unified Theory: The Search for Truth The Adversary System and the Search for Truth Truth, Reliability, and Bayesianism Applications of Quasi‐objective Bayesianism References Further Reading.

It is argued that the standard way that the criminal justice debate regarding the permissible extent of wrongful convictions is cast is fundamentally flawed. In particular, it is claimed that there is an inherent danger in focussing our attention in this debate on different ways of measuring the probabilistic likelihood of wrongful conviction and then evaluating whether these probabilities are unacceptably high. This is because such probabilistic measures are clumsy ways of capturing the level of risk involved, to the extent (...) that a defendant can be subject to an unacceptably high level of legal risk in this regard even where the relevant probabilities are very low. An alternative conception of legal risk – one that is primarily cast along modal rather than probabilistic lines – is set out which offers a much better way of framing the debate regarding what would be an acceptable level of wrongful conviction. It is further argued that with this modal conception of legal risk in play we can capture an important necessary condition that should be imposed on legal evidence, one that has application beyond the context of the criminal trial. (shrink)

This essay is an accessible introduction to the proof paradox in legal epistemology. -/- In 1902 the Supreme Judicial Court of Maine filed an influential legal verdict. The judge claimed that in order to find a defendant culpable, the plaintiff “must adduce evidence other than a majority of chances”. The judge thereby claimed that bare statistical evidence does not suffice for legal proof. -/- In this essay I first motivate the claim that bare statistical (...) class='Hi'>evidence does not suffice for legal proof. I then introduce and motivate a knowledge-centred explanation of this fact. The knowledge-centred explanation rests on two premises. The first is that legal proof requires knowledge of culpability. The second is that one cannot attain knowledge that p from bare statistical evidence that p. To motivate the second premise, I suggest that beliefs based on bare statistical evidence fail to be safe—they could easily be wrong—and bare statistical evidence cannot eliminate relevant alternatives. -/- I then cast doubt on the first premise; I argue that legal proof does not require knowledge. I thereby dispute the knowledge-centred explanation of the inadequacy of bare statistical evidence for legal proof. Instead of appealing to the nature of knowledge, I suggest we should seek a more direct explanation by appealing to those more foundational epistemic properties, such as safety or eliminating relevant alternatives. (shrink)

Arguments on legal evidence rely on generalizations, that link a certain circumstance to a certain hypothesis and warrants the claim that the circumstance makes the hypothesis more probable. Some generalizations are acceptable and others are unacceptable. A generalization can be unacceptable on at least four different grounds. A false generalization is unacceptable because membership in the reference class does not increase the probability of the hypothesis. A non-robust generalization is unacceptable because it uses a reference class that is (...) too heterogeneous. A biastriggering generalization is unacceptable because decision makers are inclined to overestimate the evidentiary value of membership in the reference class. A discriminating generalization is unacceptable because it puts members in the reference class in an unfair disadvantage. Research funded by the Swedish Research Council. (shrink)

With special attention being paid to recent developments in Artificial Intelligence and the Law, specifically related to evidentiary reasoning, this book ...

In a criminal trial, evidence is used to draw conclusions about what happened concerning a supposed crime. Traditionally, the three main approaches to modeling reasoning with evidence are argumentative, narrative and probabilistic approaches. Integrating these three approaches could arguably enhance the communication between an expert and a judge or jury. In previous work, techniques were proposed to represent narratives in a Bayesian network and to use narratives as a basis for systematizing the construction of a Bayesian network for (...) a legal case. In this paper, these techniques are combined to form a design method for constructing a Bayesian network based on narratives. This design method is evaluated by means of an extensive case study concerning the notorious Dutch case of the Anjum murders. (shrink)

This book provides an overview of computer techniques and tools — especially from artificial intelligence (AI) — for handling legal evidence, police intelligence, crime analysis or detection, and forensic testing, with a sustained discussion of methods for the modelling of reasoning and forming an opinion about the evidence, methods for the modelling of argumentation, and computational approaches to dealing with legal, or any, narratives. By the 2000s, the modelling of reasoning on legal evidence has (...) emerged as a significant area within the well-established field of AI & Law. An overview such as this one has never been attempted before. It offers a panoramic view of topics, techniques and tools. It is more than a survey, as topic after topic, the reader can get a closer view of approaches and techniques. One aim is to introduce practitioners of AI to the modelling legal evidence. Another aim is to introduce legal professionals, as well as the more technically oriented among law enforcement professionals, or researchers in police science, to information technology resources from which their own respective field stands to benefit. Computer scientists must not blunder into design choices resulting in tools objectionable for legal professionals, so it is important to be aware of ongoing controversies. A survey is provided of argumentation tools or methods for reasoning about the evidence. Another class of tools considered here is intended to assist in organisational aspects of managing of the evidence. Moreover, tools appropriate for crime detection, intelligence, and investigation include tools based on link analysis and data mining. Concepts and techniques are introduced, along with case studies. So are areas in the forensic sciences. Special chapters are devoted to VIRTOPSY (a procedure for legal medicine) and FLINTS (a tool for the police). This is both an introductory book (possibly a textbook), and a reference for specialists from various quarters. (shrink)

This paper explores whether brain images may be admitted as evidence in criminal trials under Federal Rule of Evidence 403, which weighs probative value against the danger of being prejudicial, confusing, or misleading to fact finders. The paper summarizes and evaluates recent empirical research relevant to these issues. We argue that currently the probative value of neuroimages for criminal responsibility is minimal, and there is some evidence of their potential to be prejudicial or misleading. We also propose (...) experiments that will directly assess how jurors are influenced by brain images. (shrink)

In this paper we compare causal models with reason models in the construction of Bayesian networks for legal evidence. In causal models, arrows in the network are drawn from causes to effects. In a reason model, the arrows are instead drawn towards the evidence, from factum probandum to factum probans. We explore the differences between causal models and reason models and observe several distinct advantages with reason models. Reason models are better aligned with the philosophy of Bayesian (...) inference, as they model reasons for up-dating beliefs. Reason models are better suited for measuring the combined support of the evidence, and a prior probability of guilt that reflects the number of possible perpetrators is accommodated more easily with reason models. (shrink)

In a criminal trial, a judge or jury needs to reason about what happened based on the available evidence, often including statistical evidence. While a probabilistic approach is suitable for analysing the statistical evidence, a judge or jury may be more inclined to use a narrative or argumentative approach when considering the case as a whole. In this paper we propose a combination of two approaches, combining Bayesian networks with scenarios. Whereas a Bayesian network is a popular (...) tool for analysing parts of a case, constructing and understanding a network for an entire case is not straightforward. We propose an explanation method for understanding a Bayesian network in terms of scenarios. This method builds on a previously proposed construction method, which we slightly adapt with the use of scenario schemes for the purpose of explaining. The resulting structure is explained in terms of scenarios, scenario quality and evidential support. A probabilistic interpretation of scenario quality is provided using the concept of scenario schemes. Finally, the method is evaluated by means of a case study. (shrink)

The COVID-19 Law Lab platform enables quantitative representation of epidemic law and policies in a given country for multiple years, enabling governments and researchers to compare countries, and learn about the impacts and drivers of policy choices. The Law Lab initiative is designed to address the urgent need for quality legal information to support the study of how law and policy can be used to effectively manage this, and future, pandemic(s).

While courts depend on expert opinions in reaching sound judgments, the role of the expert witness in legal proceedings is associated with a litany of problems. Perhaps most prevalent is the question of under what circumstances should testimony be admitted as expert opinion. We review the changing policies adopted by American courts in an attempt to ensure the reliability and usefulness of the scientific and technical information admitted as evidence. We argue that these admissibility criteria are best seen (...) in a dialectical context as a set of critical questions of the kind commonly used in models of argumentation. (shrink)

Lennart Åqvist (1992) proposed a logical theory of legal evidence, based on the Bolding-Ekelöf of degrees of evidential strength. This paper reformulates Åqvist's model in terms of the probabilistic version of the kappa calculus. Proving its acceptability in the legal context is beyond the present scope, but the epistemological debate about Bayesian Law isclearly relevant. While the present model is a possible link to that lineof inquiry, we offer some considerations about the broader picture of thepotential of (...) AI & Law in the evidentiary context. Whereas probabilisticreasoning is well-researched in AI, calculations about the threshold ofpersuasion in litigation, whatever their value, are just the tip of theiceberg. The bulk of the modeling desiderata is arguably elsewhere, if one isto ideally make the most of AI's distinctive contribution as envisaged forlegal evidence research. (shrink)

A leading expert in informal logic, Douglas Walton turns his attention in this new book to how reasoning operates in trials and other legal contexts, with special emphasis on the law of evidence. The new model he develops, drawing on methods of argumentation theory that are gaining wide acceptance in computing fields like artificial intelligence, can be used to identify, analyze, and evaluate specific types of legal argument. In contrast with approaches that rely on deductive and inductive (...) logic and rule out many common types of argument as fallacious, Walton’s aim is to provide a more expansive view of what can be considered "reasonable" in legal argument when it is construed as a dynamic, rule-governed, and goal-directed conversation. This dialogical model gives new meaning to the key notions of relevance and probative weight, with the latter analyzed in terms of pragmatic criteria for what constitutes plausible evidence rather than truth. (shrink)

In order to perform certain actions – such as incarcerating a person or revoking parental rights – the state must establish certain facts to a particular standard of proof. These standards – such as preponderance of evidence and beyond reasonable doubt – are often interpreted as likelihoods or epistemic confidences. Many theorists construe them numerically; beyond reasonable doubt, for example, is often construed as 90 to 95% confidence in the guilt of the defendant. -/- A family of influential cases (...) suggests standards of proof should not be interpreted numerically. These ‘proof paradoxes’ illustrate that purely statistical evidence can warrant high credence in a disputed fact without satisfying the relevant legal standard. In this essay I evaluate three influential attempts to explain why merely statistical evidence cannot satisfy legal standards. (shrink)

The relation of normic support offers a novel solution to the proof paradox: a paradox in evidence law arising from legal cases involving merely statistical evidence (Smith 2018). Central to the normic support solution has been the thesis that merely statistical evidence cannot confer normic support. However, it has been observed that there are exceptions to this: there exist cases where merely statistical evidence can give rise to normic support (Blome-Tillmann 2020). If correct, this fact (...) seems to undermine the normic support solution to the proof paradox. This paper explores a resolution: normic support can resolve the proof paradox even though merely statistical evidence sometimes gives rise to normic support. The key to understanding this resolution lies with a source of evidential support that arises out of bodies of evidence that involve *character evidence* (Colyvan, et al. 2001). It turns out that character evidence can provide normic support when it is grounded in our knowledge of a certain kind of disposition individuals can have: *goal-directed dispositions*. The upshot is the recovery of the normic support solution to the puzzle of whether statistical evidence can meet legal standards of proof. (shrink)

Background: Debates over legalisation of physician-assisted suicide or euthanasia often warn of a “slippery slope”, predicting abuse of people in vulnerable groups. To assess this concern, the authors examined data from Oregon and the Netherlands, the two principal jurisdictions in which physician-assisted dying is legal and data have been collected over a substantial period.Methods: The data from Oregon comprised all annual and cumulative Department of Human Services reports 1998–2006 and three independent studies; the data from the Netherlands comprised all (...) four government-commissioned nationwide studies of end-of-life decision making and specialised studies. Evidence of any disproportionate impact on 10 groups of potentially vulnerable patients was sought.Results: Rates of assisted dying in Oregon and in the Netherlands showed no evidence of heightened risk for the elderly, women, the uninsured , people with low educational status, the poor, the physically disabled or chronically ill, minors, people with psychiatric illnesses including depression, or racial or ethnic minorities, compared with background populations. The only group with a heightened risk was people with AIDS. While extralegal cases were not the focus of this study, none have been uncovered in Oregon; among extralegal cases in the Netherlands, there was no evidence of higher rates in vulnerable groups.Conclusions: Where assisted dying is already legal, there is no current evidence for the claim that legalised PAS or euthanasia will have disproportionate impact on patients in vulnerable groups. Those who received physician-assisted dying in the jurisdictions studied appeared to enjoy comparative social, economic, educational, professional and other privileges. (shrink)

The law views with suspicion statistical evidence, even evidence that is probabilistically on a par with direct, individual evidence that the law is in no way suspicious of. But it has proved remarkably hard to either justify this suspicion, or to debunk it. In this paper, we connect the discussion of statistical evidence to broader epistemological discussions of similar phenomena. We highlight Sensitivity – the requirement that a belief be counterfactually sensitive to the truth in a (...) specific way – as a way of epistemically explaining the legal suspicion towards statistical evidence. Still, we do not think of this as a satisfactory vindication of the reluctance to rely on statistical evidence. Knowledge – and Sensitivity, and indeed epistemology in general – are of little, if any, legal value. Instead, we tell an incentive-based story vindicating the suspicion towards statistical evidence. We conclude by showing that the epistemological story and the incentive-based story are closely and interestingly related, and by offering initial thoughts about the role of statistical evidence in morality. (shrink)

Are rights to privacy consistent with sexual equality? In a brief, but influential, article Catherine MacKinnon trenchantly laid out feminist criticisms of the right to privacy. In “Privacy v. Equality: Beyond Roe v. Wade” she linked familiar objections to the right to privacy and connected them to the fate of abortion rights in the U.S.A. (MacKinnon, 1983, 93-102). For many feminists, the Supreme Court’s decision in Roe v. Wade (1973) had suggested that, notwithstanding a dubious past, legal rights to (...) privacy might serve feminist objectives, and prove consistent with sexual equality. By arguing that Roe’s privacy justification of abortion rights was directly responsible for the weakness and vulnerability of abortion rights in America, MacKinnon took aim at feminist hopes for the right to privacy at their strongest point. Maintaining that Roe’s privacy justification of abortion is intimately, and not contingently, related to the Supreme Court’s subsequent decision in Harris v. McRae, (1980) MacKinnon concluded that privacy rights cannot be reconciled with the freedom and equality of women, and so can have no place in a democracy.1 In Harris, the Supreme Court held that the State need not provide Medicaid coverage for abortions that are necessary to preserve the health, but not the life, of a pregnant woman, effectively depriving poor women of almost all state aid for abortions.2 Moreover, the Court’s subsequent decision in Bowers v . Hardwick (1986) appeared to confirm the truth of MacKinnon’s observation – though this case concerned gay rights, rather than abortion rights, and occurred several years after MacKinnon’s condemnation of Harris. -/- This paper examines MacKinnon’s claims about the relationship of rights to privacy and equality in light of the reasoning in Harris and Bowers. When we contrast the Majority and Minority decisions in these cases, it shows, we can distinguish interpretations of the right to privacy that are consistent with sexual equality from those that are not. This is not simply because the two differ in their consequences – though they do - but because the former, unlike the latter, rely on empirical and normative assumptions that would justify sexual inequality whatever right they were used to interpret. So while I agree with MacKinnon that the Majority’s interpretation of the right to privacy in Harris is inconsistent with the equality of men and women, I show that there is no inherent inconsistency in valuing both privacy and equality, and no reason why we must chose to protect the one, rather than the other. Indeed, an examination of MacKinnon’s article, I suggest, can help us to see why rights to privacy can be part of a scheme of democratic rights, and how we might go about democratising the right to privacy in future. To avoid confusion I should emphasise that my arguments are of a philosophical, not a legal, nature. Thus, I will be ignoring the specifically legal and constitutional aspects of MacKinnon’s article, and of the Supreme Court decisions, in order to bring their philosophical significance into focus. -/- . (shrink)

Many legal disputes turn on scientific, especially statistical, evidence. Traditionally scientists have accepted only that statistical evidence which satisfies a 95 percent (or 99 percent) rule — that is, only evidence which has less than five percent (or one percent) probability of resulting from chance.The rationale for this rule is the reluctance of scientists to accept anything less than the best-supported new knowledge. The rule reflects the internal needs of scientific practice. However, when uncritically adopted as (...) a rule for admitting legal evidence, the seemingly innocuous 95 percent rule distorts the balance of interests historically protected by the legal system. In particular, plaintiffs in toxic tort and employment discrimination suits are effectively held to a heavier burden of proof in showing that their injuries were more probably than not caused by the defendant's actions. The result is that too many victims of toxic torts or employment discrimination cannot win legal redress for their injuries. (shrink)

Both opponents and proponents of the death penalty express faith in science and in DNA evidence to justify their positions. This article examines the production of forensic evidence as a social activity and suggests that tendencies toward bias and error may not apply symmetrically in inculpation and exoneration contexts.

Medicine, like law, is a pragmatic, probabilistic activity. Both require that decisions be made on the basis of available evidence, within a limited time. In contrast to law, medicine, particularly evidence-based medicine as it is currently practiced, aspires to a scientific standard of proof, one that is more certain than the standards of proof courts apply in civil and criminal proceedings. But medicine, as Dr. William Osler put it, is an "art of probabilities," or at best, a "science (...) of uncertainty." One can better practice medicine by using other evidentiary standards in addition to the "scientific." To employ only the scientific standard of proof is inappropriate, if not impossible; furthermore, as this review will show, its application in medicine is fraught with bias. Evidence is information. It supports or undermines a proposition, whether a hypothesis in science, a diagnosis in medicine, or a fact or point in question in a legal investigation. In medicine, physicians marshal evidence to make decisions on how to best prevent, diagnose, and treat disease, and improve health. In law, courts decide the facts and render justice. Judges and juries assess evidence to establish liability, to settle custody and medical issues, and to determine a defendant's guilt or innocence. (shrink)

The aim of this essay is to develop a coherence theory for the justification of evidentiary judgments in law. The main claim of the coherence theory proposed in this article is that a belief about the events being litigated is justified if and only if it is a belief that an epistemically responsible fact finder might hold by virtue of its coherence in like circumstances. The article argues that this coherentist approach to evidence and legal proof has the (...) resources to meet some of the main objections that may be addressed against attempts to analyze the justification of evidentiary judgments in law in coherentist terms. It concludes by exploring some implications of the proposed version of legal coherentism for a jurisprudence of evidence. (shrink)

Proposed lie-detection technology based on neuroscience poses significant challenges for the law. The law must respond to the science with an adequate understanding of such evidence, its significance, and its limitations. This paper makes three contributions toward those ends. First, it provides an account of the preliminary neuroscience research underlying this proposed evidence. Second, it discusses the nature and significance of such evidence, how such evidence would fit with legal practices and concepts, and its potential (...) admissibility. Finally, it analyzes the constitutional protections that may limit the compelled production of such evidence. (shrink)

This article focuses on the events surrounding a homosexual Romanian man's attempt to be recognized as a refugee in Britain. Numerous themes emerge such as the nature of authenticity, knowledge, identity, pleasure, evidence and the homosexual refugee as being caught in between two legal apparatuses (that is, fleeing from the hostility of one legal regime and then trying to gain refugee status, and thus legal protection, via a British Immigration Tribunal). In this article, the corporeality and (...) sensuality of legal practices are exposed in the form of `practices of truth'. That is, in this case medico-legal `living individuals' were to perceive, hear, speak, touch and penetrate the `secrets' of Mr Vraciu's body in order to authenticate his sexual identity for the purposes of law. This case also demonstrates the existence of a differend between what I describe as the self-knowledge of homosexuality and the `legal' fact-based, or authorized knowledge of homosexual identity produced through practices of truth. (shrink)

Many epistemological terms, such as investigation, inquiry, argument, evidence, and fact were established in law well before being associated with science. However, while legal proof remained qualified by standards of ‘moral certainty’, scientific proof attained a reputation for objectivity. Although most forms of legal evidence continue to be treated as fallible ‘opinions’ rather than objective ‘facts’, forensic DNA evidence increasingly is being granted an exceptional factual status. It did not always enjoy such status. Two decades (...) ago, the scientific status of forensic DNA evidence was challenged in the scientific literature and in courts of law, but by the late 1990s it was being granted exceptional legal status. This paper reviews the ascendancy of DNA profiling, and argues that its widely-heralded objective status is bound up with systems of administrative accountability. The ‘administrative objectivity’ of DNA evidence rests upon observable and reportable bureaucratic rules, records, recording devices, protocols, and architectural arrangements. By highlighting administrative sources of objectivity, this paper suggests that DNA evidence remains bound within the context of ordinary organisational and practical routines, and is not a transcendent source of ‘truth’ in the criminal justice system. (shrink)

A Bayesian network (BN) is a graphical model of uncertainty that is especially well suited to legal arguments. It enables us to visualize and model dependencies between different hypotheses and pieces of evidence and to calculate the revised probability beliefs about all uncertain factors when any piece of new evidence is presented. Although BNs have been widely discussed and recently used in the context of legal arguments, there is no systematic, repeatable method for modeling legal (...) arguments as BNs. Hence, where BNs have been used in the legal context, they are presented as completed pieces of work, with no insights into the reasoning and working that must have gone into their construction. This means the process of building BNs for legal arguments is ad hoc, with little possibility for learning and process improvement. This article directly addresses this problem by describing a method for building useful legal arguments in a consistent and repeatable way. The method complements and extends recent work by Hepler, Dawid, and Leucari (2007) on object-oriented BNs for complex legal arguments and is based on the recognition that such arguments can be built up from a small number of basic causal structures (referred to as idioms). We present a number of examples that demonstrate the practicality and usefulness of the method. (shrink)

As the health care system transitions to a precision medicine approach that tailors clinical care to the genetic profile of the individual patient, there is a potential tension between the clinical uptake of new technologies by providers and the legal system's expectation of the standard of care in applying such technologies. We examine this tension by comparing the type of evidence that physicians and courts are likely to rely on in determining a duty to recommend pharmacogenetic testing of (...) patients prescribed the oral anti-coagulant drug warfarin. There is a large body of inconsistent evidence and factors for and against such testing, but physicians and courts are likely to weigh this evidence differently. The potential implications for medical malpractice risk are evaluated and discussed. (shrink)

The facts to be proven in a lawsuit can be more or less probable. But the recognition of the relevant facts may require discretion or evaluative operations; moreover, a just and equitable interpretation of a contract may depend on what the contracting parties knew about the intentions of each other. Can, e.g., negligence be more or less probable? Can Ought be proven? There is, however, a structural similarity between legal interpretation and the evalution of evidence and not only (...) an intertwinement between the so-called questions of fact and the questions of law. A number of situations is briefly analysed: the interpretation of contracts, the interest of the child, the basic concepts of the law of torts and the criminal intent. (shrink)

Walton’s book aims to supply a fresh method for evaluating logical reasoning and legal argumentation. Drawn from philosophy, law and science, Walton’s method rests on a theory of “plausibilistic” reasoning or “probabilism”. According to plausibilistic reasoning, we can logically infer conclusions from a set of premises even though the premises are neither definite nor of a measurable probability. We may tentatively draw such inferences so long as they rest on generally valid premises. To illustrate this method, Walton cites a (...) famous example from Wigmore: A man had no money before a robbery, but suddenly came into a great deal of money following the robbery. It is therefore plausible to infer that the man committed the robbery. (shrink)

We argue that legal argumentation, as the subject matter as well as a special subfield of Argumentation Studies (AS), has to be examined by making skilled use of the full panoply of tools such as argumentation and story schemes which are at the forefront of current work in AS. In reviewing the literature, we make explicit our own methodological choices (particularly regarding the place of normative deliberation in practical reasoning) and then illustrate the implications of such an approach through (...) the analysis of a case study in the English law of evidence. We argue that a clear distinction must be drawn between practical argumentation and stories. Because of the institutional separation between legal judgment and fact-finding in common-law jury trials, we argue for the combination of argument and story-based analysis. (shrink)

El estudio de dos formularios notariales del siglo vii/xiii, uno sirio y el otro andalusí, muestra que el discurso sobre las modalidades de comunicación escrita preceptuadas para los jueces refleja una estrecha relación entre la doctrina y la realidad de la práctica legal. Uno de los aspectos de esta relación es el cambio que tuvo que experimentar la doctrina discursiva bajo la presión de las prácticas judiciales cotidianas.

Many jurisdictions prohibit or severely restrict the use of evidence about a defendant’s character to prove legal culpability. Situationists, who argue that conduct is largely determined by situational features rather than by character, can easily defend this prohibition. According to situationism, character evidence is misleading or paltry. -/- Proscriptions on character evidence seem harder to justify, however, on virtue ethical accounts. It appears that excluding character evidence either denies the centrality of character for explaining conduct—the (...) situationist position—or omits probative evidence. Situationism is, after all, presented as antithetical to virtue ethics. -/- This essay provides a virtue ethical defense of character evidence exclusion rules. We show that existing virtue ethical rebuttals to situationism themselves support prohibitions on character evidence; even if behavior arises from stable character traits, character evidence should be prohibited. In building our case, we provide a taxonomy of kinds of character judgment and reconcile the ubiquity and reasonableness of character judgments in ordinary life with the epistemic legitimacy of character evidence prohibitions in law. (shrink)

This article presents original empirical data generated from the Crown Prosecution Service (CPS) Pilot Evaluation of pre-trial witness interviewing (PTWI) in England and Wales. Section 1 introduces the PTWI Pilot and describes the methodological strengths and limitations of our qualitative socio-legal study. Forming the richly documented empirical core of the article, Sections 2–5 identify the principal considerations which seemed to influence case selection for Pilot interviews. An overlapping collection of evidentiary, strategic and circumstantial factors encouraged prosecutors to resort to (...) PTWI, whilst other, countervailing considerations were apprehended as disincentives. Assessments of witness credibility were central to prosecutors’ attempts to balance these competing factors. Section 6 concludes by underlining the potential of qualitative socio-legal studies to promote more nuanced understandings of criminal process, and by extension to make practical contributions to evidence-based criminal procedure reform. (shrink)