Overview and Meaning of Identification/Individualization

Two traditional inferential schemes for the question of identification of source are presented. The first leads to decisions (typically individualization or exclusion) and the second to the provision of corroborative information (e.g., possible, probable, very probable association, etc.). Both of these schemes are traditionally applied with reference to a relevant population size set to its maximum in what has been called an open set framework (or the Earth population paradigm). One of them requires, in addition, a decision step implying a cost/benefit analysis. The logical difficulties associated with both schemes are exposed to a final question if these practices are reasonable for forensic cases. An alternative scheme, the Bayesian interpretation framework, overcomes most of these difficulties, in particular, by relaxing the necessity of adopting a given prior framework and applying decision thresholds. It provides to the forensic scientist and the fact finder clarification of their duties and a coherent way of assessing and presenting identification evidence.