Scientific Evidence in Europe -- Admissibility, Evaluation and Equality of Arms

This study was commissioned by the European Committee on Crime Problems at the Council of Europe to describe and discuss the standards used to asses the admissibility and appraisal of scientific evidence in various member countries. After documenting cases in which faulty forensic evidence seems to have played a critical role, the authors describe the legal foundations of the issues of admissibility and assessment of the probative value in the field of scientific evidence, contrasting criminal justice systems of accusatorial and inquisitorial tradition and the various risks that they pose in terms of equality of arms. Special attention is given to communication issues between lawyers and scientific experts. The authors eventually investigate possible ways of improving the system. Among these mechanisms, emphasis is put on the adoption of a common terminology for expressing the weight of evidence. It is also proposed to adopt an harmonized interpretation framework among forensic experts rooted in good practices of logical inference.The foreword was authored by D. Michael Risinger, Seton Hall University School of La

Ce que la justice fait dire à l’ADN (et que l’ADN ne dit pas vraiment). Etude qualitative de l’évaluation de la preuve par ADN dans le système judiciaire pénal suisse

La recherche dont il est ici question est un projet interdisciplinaire visant à réconcilier les points de vue juridique, criminologique et forensique d’une problématique très actuelle : l’interprétation de la preuve par ADN par le juge pénal. Si, juridiquement, les relations entre le juge et l’expert sont clairement établies, en ce sens que le juge doit apprécier la preuve par ADN librement, dans les faits, la situation est ambiguë, puisque le juge reconnaît les limites de ses compétences en nommant un expert, tout en conservant le droit de s’écarter des conclusions de celui-ci s’il l’estime pertinent. Cette règle de libre appréciation des preuves existe pour tout type d’expertise et depuis longtemps, mais, à notre sens, la preuve par ADN présente à cet égard des difficultés nouvelles : souvent qualifiée de reine des preuves, la preuve par ADN a la réputation de « désigner le coupable ». Pourtant, elle repose sur des techniques d’analyse complexes et les résultats évaluatifs sont présentés par les experts sous forme de probabilités, deux éléments qui rendent l’appréciation de la preuve particulièrement compliquée pour un juge qui ne jouit en général que de connaissances scientifiques limitées. Ces dernières décennies, de nombreuses recherches menées dans le monde anglo-saxon ont permis de mettre en évidence les difficultés rencontrées par les tribunaux lorsqu’il s’agit d’évaluer ce type de preuves scientifiques. Sur la base d’une étude de la jurisprudence ainsi que d’entretiens réalisés avec des acteurs de la justice pénale, l’étude met en lumière l’attitude des juristes suisses face à la preuve par ADN et à leurs auxiliaires scientifiques, et les défis que cette collaboration représente au quotidien dans un système de justice non adversarial

The Decisional Nature of Probability and Plausibility Assessments in Juridical Evidence and Proof

The quantification of uncertainty is a key topic in different theories and accounts of the legal process, ranging from probabilism to explanationism. These accounts invoke probability to various extents. For legal probabilism, probability is the single core concept, whereas other accounts, such as the relative plausibility theory, give it a more limited role, as one consideration among others. At the same time, controversies persist about the nature of probability and the value it may add to the understanding of the broad range of aspects that characterise the legal process. These controversies arise, in part, from the fact that probability itself is the object of confusing debates in many scientific disciplines. In view of these intricacies, this paper argues that the critical analysis and clarification of how to understand and use probability meaningfully remains a topic worthy of investigation across different theoretical perspectives. The first part of this paper critically examines a selection of persisting misconceptions about probability and objections against its use, based on discussions presented in recent evidence law literature. Part II of this paper will blend this discussion with a particular view of probability, interpreted as a personal decision, rarely acknowledged in legal literature. Using a multidisciplinary perspective and a thorough review of historical sources, we illustrate and discuss how the understanding of probability assertion as a decision promotes transparency, honesty, accountability and justifiability. This decisional perspective is further developed and discussed in Part III to show that its logical ingredients underpin key concepts of different theoretical accounts, in particular the assertion of degrees of belief, assessments of relative plausibility and verdicts about ultimate issues at trial. Overall, the paper makes the point that the isolated debates over probability, legal probabilism and reasoning under uncertainty misconceive the primary problem of the legal process, which is decision-making under uncertainty. The proposed decisional perspective clarifies these issues both analytically and descriptively, and resolves divergencies between ostensibly competing concepts such as probability and relative plausibility

Auf Fingerabdrücke ist nicht immer Verlass

Fingerabdrucke sind trügerisch. Selbst wenn Experten Fingerspuren vergleichen, können Fehler auftreten. Die endgültige Zuordnung einer Spur zu einem Verdächtigen sollte Sache der Gerichte sein, nicht der Experten

Understanding the logic of forensic identification decisions (without numbers)

Over the past few years, a movement has been initiated among forensic science researchers and practitioners, in Switzerland and across Western criminal justice systems more generally, to shift away from categorical assertions of common source (e.g., «this crime scene mark and this control print come from the same person») towards new reporting formats that consider expert conclusions as decisions (e.g., an «identification» or «exclusion» is a decision made by the forensic examiner). As this movement gains momentum, there remains disagreement on how exactly the notion of decision ought to be understood. The call for improvement of the understanding of the logical tenets of forensic identification decisions faces the obstacle that many forensic practitioners shy away from formal and quantitative approaches (e.g., decision theory). The purpose of this contribution is to show that the logical essentials of forensic identification decisions can be captured and conveyed without going into the details of the mathematics of decision theory. We will then present and defend the view that forensic identification requires assessments and value judgments that go beyond the forensic practitioner's area of competence and that this fact requires a reassessment of the distribution of responsibilities between experts and other participants in the legal process