Much attention has been
given to estimating the probability of obtaining false matches between
DNA samples from an innocent suspect and those crime scene but
considerably less attention has been given to the critical issue of
determining the probability of guilt given a match.  Using Bayes' Rule
and trivial algebra, we develop a measure of the strength of DNA
evidence that indicates the amount of incriminating evidence needed in
combination with DNA match evidence to meet a given conviction
standard.  Based on current standards and practices, we use this
measure to explore legal ramifications of DNA match and mismatch
evidence.