After uniqueness: the evolution of forensic science opinions

Big changes are occurring in forensic science, particularly among experts who compare the patterns found in fingerprints, footwear impressions, toolmarks, handwriting, and the like. Forensic examiners are reaching conclusions in new ways and changing the language they use in reports and testimony. This article explains these changes and the challenges they pose for lawyers and judges

独特性之后:法庭科学意见的演进 (After uniqueness: the evolution of forensic science opinions)

Big Changes are occurring in forensic science, particularly among experts who compare the patterns found in fingerprints, footwear impressions, toolmarks, handwriting, and the like. Forensic examiners are reaching conclusions in new ways and changing the language they use in reports and testimony. This article explains these changes and the challenges they pose for lawyers and judges

Magistrats et experts scientifiques: une mésentente cordiale

Que ce soit sous la forme d’expertises formelles, de rapports d’analyse, de laboratoire ou de police, les éléments de preuve scientifiques jouent souvent un rôle important dans les affaires pénales. Toutefois, leur utilisation dans l’établissement des faits n’est pas toujours optimale. Cela provient notamment du fait que magistrats instructeurs et auxiliaires scientifiques ont souvent une perception faussée ou déformée des attentes, besoins et compétences de leurs partenaires dans la procédure. Cette incompréhension peut résulter dans des malentendus, pertes de temps et gaspillages de moyens financiers, mais aussi, parfois, dans une appréciation erronée des faits. Cette contribution a pour but d’explorer les représentations que se font les acteurs de la justice pénale du rôle de l’indice scientifique et d’offrir quelques pistes de réflexions afin de dépasser les obstacles les plus courants à une bonne communication entre eux

A Bayesian network approach to the database search problem in criminal proceedings

Abstract Background The ‘database search problem’, that is, the strengthening of a case - in terms of probative value - against an individual who is found as a result of a database search, has been approached during the last two decades with substantial mathematical analyses, accompanied by lively debate and centrally opposing conclusions. This represents a challenging obstacle in teaching but also hinders a balanced and coherent discussion of the topic within the wider scientific and legal community. This paper revisits and tracks the associated mathematical analyses in terms of Bayesian networks. Their derivation and discussion for capturing probabilistic arguments that explain the database search problem are outlined in detail. The resulting Bayesian networks offer a distinct view on the main debated issues, along with further clarity. Methods As a general framework for representing and analyzing formal arguments in probabilistic reasoning about uncertain target propositions (that is, whether or not a given individual is the source of a crime stain), this paper relies on graphical probability models, in particular, Bayesian networks. This graphical probability modeling approach is used to capture, within a single model, a series of key variables, such as the number of individuals in a database, the size of the population of potential crime stain sources, and the rarity of the corresponding analytical characteristics in a relevant population. Results This paper demonstrates the feasibility of deriving Bayesian network structures for analyzing, representing, and tracking the database search problem. The output of the proposed models can be shown to agree with existing but exclusively formulaic approaches. Conclusions The proposed Bayesian networks allow one to capture and analyze the currently most well-supported but reputedly counter-intuitive and difficult solution to the database search problem in a way that goes beyond the traditional, purely formulaic expressions. The method’s graphical environment, along with its computational and probabilistic architectures, represents a rich package that offers analysts and discussants with additional modes of interaction, concise representation, and coherent communication

La probabilità come strumento per una coerente valutazione della prova scientifica

Tutti gli attori del sistema giudiziario si trovano quotidianamente di fronte alla necessità di operare in condizioni di incertezza. Si prenda, a titolo di esempio, la fase di valutazione della prova scientifica, la necessità della sua corretta integrazione con le altre informazioni pertinenti, o la quantificazione del valore da accordare alle ipotesi d'interesse per la Corte. Questo capitolo mette l'accento sull'inevitabilità dell'incertezza, sia per le scienze forensi che per quelle giuridiche, e sulla necessità di fare riferimento alla probabilità in quanto metrica coerente per la sua quantificazione e gestione. Il metodo di ragionamento probabilistico è presentato in dettaglio anche attraverso una serie di esempi che fanno riferimento alla gestione della prova genetica del DNA. sono inoltre riportati e illustrati i principali errori di interpretazione commessi dai periti. Un altro aspetto di forte interesse è rappresentato dalla gestione congiunta di più evidenze, che si traduce inevitabilmente in una crescente difficoltà in termini di calcolo delle probabilità. A tal fine, il capitolo include la presentazione dei modelli grafici probabilistici, che rappresentano un metodo di ragionamento formale idoneo ad assistere sia gli scienziati forensi che i giudici nella gestione della complessità derivante da legami di dipendenza che possono esistere tra diverse evidenze. È d'avviso degli autori, che il giurista moderno dovrebbe avere almeno una formazione di base su queste tematiche, ed in particolare in termini di probabitità, al fine di essere più consapevole e attento rispetto alla gestione e all'interpretazione dell'incertezza

On the Bayesian approach to forensic age estimation of living individuals

Forensic age estimation, a branch of forensic science, has received renewed attention lately mainly due to societal migration phenomena. And yet, the interpretation of age-related evidence is still largely neglected as a field, the literature being usually limited to technical discussions strictly pertaining to the statistical methodologies to be used in estimation process. This short communication aims to highlight the fundamental role of evidence evaluation and interpretation in forensic age estimation. We illustrate why the Bayesian approach represents the best choice in such a perspective