A Practical Guide for the Formulation of Propositions in the Bayesian Approach to DNA Evidence Interpretation in an Adversarial Environment |
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| Authors: | Simone Gittelson Ph.D. Tim Kalafut Ph.D. Steven Myers M.S. Duncan Taylor Ph.D. Tacha Hicks Ph.D. Franco Taroni Ph.D. Ian W. Evett D.Sc. Jo‐Anne Bright Ph.D. John Buckleton D.Sc. |
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| Affiliation: | 1. Department of Biostatistics, University of Washington, Seattle, WA;2. U.S. Army Criminal Investigation Laboratory, Forest Park, GA;3. California Department of Justice, Jan Bashinski DNA Laboratory, Richmond, CA;4. Forensic Science South Australia, Adelaide, SA, Australia;5. School of Criminal Justice, University of Lausanne, Lausanne, Switzerland;6. Foundation for Continuing Education UNIL‐EPFL, Lausanne, Switzerland;7. Principal Forensic Services Ltd, Bromley, UK;8. ESR Ltd, Auckland, New Zealand |
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| Abstract: | The interpretation of complex DNA profiles is facilitated by a Bayesian approach. This approach requires the development of a pair of propositions: one aligned to the prosecution case and one to the defense case. This note explores the issue of proposition setting in an adversarial environment by a series of examples. A set of guidelines generalize how to formulate propositions when there is a single person of interest and when there are multiple individuals of interest. Additional explanations cover how to handle multiple defense propositions, relatives, and the transition from subsource level to activity level propositions. The propositions depend on case information and the allegations of each of the parties. The prosecution proposition is usually known. The authors suggest that a sensible proposition is selected for the defense that is consistent with their stance, if available, and consistent with a realistic defense if their position is not known. |
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| Keywords: | forensic science forensic DNA likelihood ratio propositions Bayesian approach DNA mixtures |
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