NCJ Number
213442
Journal
Journal of Forensic Identification Volume: 56 Issue: 2 Dated: April 2006 Pages: 255-280
Date Published
April 2006
Length
26 pages
Annotation
This article discusses the deliberations and the recommendations of the Conclusion Scale Committee (CSC) of the European Network of Forensic Science Institutes (ENFSI) regarding a harmonized "Six-Level Conclusion Scale" for forensic analysts' comparison decisions regarding shoeprints and toolmarks.
Abstract
The main aim of the CSC was to produce a conclusion scale that would enable practitioners to understand the meaning of conclusions by forensic examiners of shoeprints and toolmarks across Europe, taking into account the different criminal justice systems. The theoretical fundamentals of the harmonized conclusion scale developed by CSC take reflect interpretation models based on the Bayes' rule; however, members of the CSC are not in agreement about the use of these models of mathematical probability when it comes to comparing shoeprints and toolmarks. The majority of the CSC members emphasize that in many countries the practice in court is for judges and juries to get clear answers on the probability that the questioned shoe sole produced the print at the crime scene. The majority of the CSC members apply all three parts of the odds form of the Bayes' rule, using only scientific interpretations by means of the Principle of Causality and the Principle of Maximum Entropy. The six-level scale proposed by CSC allows for use of a likelihood ratio (partial Bayes' rule) and a probability conclusion (full Bayes' rule, classical approach). The levels attempt to reflect the analyst's degree of certainty about the match regardless of whether a likelihood ratio or probability assessment is used. 4 tables, 1 figure, 40 references, and appended informative discussions about Bayesian approaches (pro and con) between experts