Mike Redmayne

Expert evidence and criminal justice

1. Introduction 2. Constructing Cases with Science 3. Probability Models in Forensic Science 4. Presenting Probabilities in Court 5. The Admissibility of Expert Evidence: (1) Evidentiary Reliability 6. The Admissibility of Expert Evidence: (2) The Rule in R. v. Turner 7. Adversarial Experts Index

Myths, relationships and coincidences: the new problems of sexual history

This article reviews recent developments in the law governing the admissibility of sexual history evidence in England and Wales. After the decision of the House of Lords in R v A (No. 2), the law reflects a consensus that the complainants sexual history with third parties is generally irrelevant to the issue of consent in rape trials. In the first part of this article, the justifications for this conclusion are questioned; it is suggested that the relevance of sexual history is a more complex issue than it is usually acknowledged to be. The second part of the article uses points made in the first to question the way in which concepts drawn from the law on similar fact evidence have been used as the admissibility framework for sexual history. Aspects of the decision in R v A are examined in detail.

The relevance of bad character

An important rule of criminal evidence is that evidence of a defendant’s previous misconduct (evidence of bad character) is prima facie inadmissible. The usual justification for this rule is that, in most cases, such evidence is either irrelevant or likely to have an unduly prejudicial effect on the fact-finder. This article questions this justification. After reviewing the psychological research on character, it examines statistical data on recidivism. The statistics suggest that those with previous convictions are much more likely to offend than are those without a criminal record, which implies that evidence of bad character will usually be sufficiently probative to justify its admission as proof of guilt. The remainder of the article examines various criticisms which can be levelled at this argument, in particular, that the recidivism data are misleading and that the way in which fact-finders reason renders evidence of bad character uninformative.

Appeals to Reason

This article considers how statistical reasoning changes conceptions of evidence and proof. Beginning with three Court of Appeal judgments in which proof is quantified, it traces the implications of statistical ways of thinking about proof through the law of criminal evidence. This leads to the bizarre conclusion that proof is, by and large, impossible. The argument then takes a more constructive turn. The way in which the presumption of innocence is conceptualised in statistical argument is criticised and it is suggested that proof depends on a precondition of trust in the way suspects are selected by the police. For that trust to be deserved, police suspects must be chosen in a legitimate manner.

Presenting Probabilities in Court: The DNA Experience

he use of probabilistic’ evidence in litigation has often been thought to cause especial problems for the legal system. Much ink has been spilt on arguments as to whether findings of liability can be based on so-called naked statistical evidence.2 Another contentious issue has been whether the use of probabilistic evidence somehow dehumanises the legal system. The claim that it does has partly been the basis for a series of decisions in which Minnesota’s Supreme Court held that scientific evidence should not be presented in probabilistic terms? Now the use of probabilistic evidence, such as DNA evidence, is confronting the courts with a new problem: that of explaining to juries just what the probability figure associated with the evidence means. At first sight this problem might seem trivial, but it is not. Britain’s Court of Appeal has had to address the question of the interpretation of DNA probabilities in a series of recent cases, but as yet it has found no unproblematic solution.4 A Committee of the United States National Research Council has also given the problem some thought, but it has offered no clear recommendation on the issue?

Character in the criminal trial

•A comprehensive analysis of the bad character provisions in the Criminal Justice Act 2003 •Explores conceptual, doctrinal, and theoretical issues underlying character evidence •Examines the use of character evidence in determining sentences. If a defendant is on trial for a crime such as burglary, to what extent should the fact that he has a previous conviction for burglary feature in his trial? Should the prosecution be allowed to tell the jury about the previous conviction as evidence that the defendant is more likely to have committed burglary? Should the judge give the defendant a longer sentence because he has a previous conviction? These are the fundamental questions examined in Character in the Criminal Trial. Including an in-depth analysis of the character evidence provisions of the Criminal Justice Act 2003, this book assesses the arguments for and against using character evidence to prove a defendants guilt. It explores the sentencing provisions in the same Act, as well as the general use of criminal record and other character evidence to aggravate and mitigate sentence. Issues examined in the course of the book include: psychological and philosophical debates about the stability of character; criminological research on recidivism and the nature of criminal careers; ethical debates about the use of prior behaviour to prove current or future offending; the process of reasoning underlying the use of bad character evidence; whether bad character evidence is prejudicial; and the use of risk assessment instruments to classify offenders as dangerous. By combining insights from law, psychology, criminology, and philosophy, Redmayne reassesses the use of character in the criminal trial and reflects on the significance of the laws increasing emphasis on character.

Similar facts, familiar obfuscation: R v Handy

rying to make sense of superior court decisions on similar fact evidence is frequently a frustrating business. The obscurity of Lord Herschell’s famous dictum in Makin v AttorneyCeneral for New South Wales’ is well known. One thinks too of the decision of the House of Lords in DPP v Boardman:2 five different judgments, all ostensibly agreeing with each other. But on closer inspection we find that it is hard to pin some of the individual judgments down to a coherent message, let alone to reconcile all of them. By way of contrast, the decision of the High Court of Australia in Pfennig v R3 is reasonably clear, insofar as it approves the approach taken in Hoch v R! But Toohey J’s judgment, in particular, contains enough odd statements about the proper role of propensity in similar fact reasoning to make one wonder what is really going on. Even some of the seemingly simpler decisions are problematic. Sixteen years after Boardman. the House of Lords revisited similar facts in DPP v P,5 this time delivering only a single judgment. In it, Lord Mackay tries to pull off the difficult task of deferring to the decision in Boardman-which is set out in a series of rather unrepresentative quotations from that case-while steering the law in a new direction. This inevitably left a number of tensions in the law.

The Law Commission's character convictions

This article assesses the proposals made by the Law Commission for England and Wales in its recent report on bad character evidence. Rather than looking at the technical details of the Commissions proposed admissibility scheme, it concentrates on the foundational principles behind it. The Commission does not propose wholescale reform of this area of the law. It recommends retaining the general rule that evidence of a defendants bad character is prima facie inadmissible. It also proposes an exception to this general rule, allowing bad character evidence to be used to attack a defendants credibility if the defendant runs his defence in a particular way. This, too, mirrors the current law, though the Commissions exception would be more tightly drawn than the present rule. Another exception to the general rule of exclusion relates to similar fact evidence. Here, the Commission recommends replacing the current rule with a more carefully structured one. It is suggested that the Commission offers no cogent justification for any of these proposals.

Evidence, Jury Trials and Witness Protection—The Auld Review of the English Criminal Courts

The publication of Auld LJs review of the English criminal courts may herald significant reform of the trial process. It is argued that recommendations to retain the jury whilst subjecting its decision-making to greater judicial control, and restricting proper research into its operation, lack a coherent foundation and may prove problematic in practice. The recommendations may enhance protection for vulnerable witnesses although proposals to increase the chances of convicting in cases of domestic violence may also create risks for victims.

Review: The Evaluation of Forensic DNA EvidenceNational Research Council Committee on DNA Forensic ScienceTHE EVALUATION OF FORENSIC DNA EVIDENCEWashington DC: National Academy Press (1996) xv + 254 pp, hb, £30.95

In 1992. while the use of DNA evidence in the US courts was the subject of considerable controversy, a Committee established by the National Research Council (NRC) published a report on the use of DNA technology in forensic science. The report proposed, among other things, a set of criteria for the calculation of DNA match probabilities which, it was hoped, would allay the fears of some of the critics of DNA evidence while still allowing such evidence to be used in the courts. As it turned out, the first NRC report (NRCl) did not end the controversy over DNA evidence, indeed, at times it seemed only to have exacerbated it. Now a second report on DNA evidence has been published under the auspices of the NRC (NRC2), updating the recommendations of NRCl on the computation of DNA match probabilities. In the four years between the publication of the two reports much has happened: the ongoing process of research into forensic genetics has lessened fears that the genetic structure of human populations invalidates the theoretical assumptions underlying match probability calculation. In turn, this has shifted the focus of the DNA debate to other matters, in particular laboratory procedures and juror comprehension of probabilistic evidence.