Customary ways of reporting on or testifying about malingering have shortco
mings. Stating an opinion "with reasonable medical certainty" tells fact-fi
nders little about how much confidence the opinion deserves; stating that a
n individual's behavior is similar to that of known malingerers does not co
nvey the information that fact-finders really need to know, which is the li
kelihood that the evaluee in question is a malingerer, given the evaluator'
s findings. Mossman and Hart (Mossman D, Hart KJ: Presenting evidence of ma
lingering to courts: insights from decision theory. Behav Sci Law 14:271-91
, 1996) recommend that mental health professionals address this problem by
using Bayes' theorem to interpret test data from evaluations. However, thes
e authors do not discuss the use of evidence obtained during interviews and
from other clinical contexts, nor do they describe a method for quantifyin
g imprecision in Bayesian probabilities. This article provides examples of
how forensic evaluators might use a Bayesian perspective to interpret clini
cal indicia of malingering observed during evaluations of adjudicatory comp
etence. The article discusses sources of imprecision in Bayesian posterior
probabilities, describes a method for characterizing that imprecision using
confidence intervals, and then presents several sample calculations that i
llustrate how interview findings change the likelihood of malingering. The
article also discusses the implications of the Bayesian approach for forens
ic evaluations and for future research on malingered incompetence.