  Forensic experts use specialized training and knowledge to enable other
members of the judicial system to make better informed and more just decisions.
Factfinders, in particular, are tasked with judging how much weight to give to
experts' reports and opinions. Many references describe assessing evidential
weight from the perspective of a forensic expert. Some recognize that
stakeholders are each responsible for evaluating their own weight of evidence.
Morris (1971, 1974, 1977) provided a general framework for recipients to update
their own uncertainties after learning an expert's opinion. Although this
framework is normative under Bayesian axioms and several forensic scholars
advocate the use of Bayesian reasoning, few resources describe its application
in forensic science. This paper addresses this gap by examining how recipients
can combine principles of science and Bayesian reasoning to evaluate their own
likelihood ratios for expert opinions. This exercise helps clarify how an
expert's role depends on whether one envisions recipients to be logical and
scientific or deferential. Illustrative examples with an expert's opinion
expressed as a categorical conclusion, likelihood ratio, or range of likelihood
ratios, or with likelihood ratios from multiple experts, each reveal the
importance and influence of validation data for logical recipients'
interpretations.
