Previously, based on the outcome of forensic analyses, experts’ conclusions expressed the likelihood of a particular source given a piece of evidence. Within the logically correct approach the likelihood of a piece of evidence is evaluated under two
rival hypotheses concerning the source of the trace. Although the new way of reporting is logically correct, whereas the old way was not (see below), the interpretation of forensic evidence using such likelihood ratios is notoriously difficult
for jurists (Fenton & Neil, 2000). Of course even before the introduction of logically correct reporting, the larger issue of difficult communication between technica forensic experts and the courts was recognized (National Research Council, 2009).
Our current focus, however, is on the specific topic of understanding likelihood ratios in forensic reporting to the courts.