The purpose of a sex offender evaluation is not to determine the likelihood of an accused individual having had committed a sex offense.  Innocence or guilt is a decision for the trier-of-fact.  Rather, a forensic psychologist’s role typically involves the sentencing phase of the court’s involvement.  The judge most often is interested in knowing a variety of facets regarding a sex offender’s psychological functioning.  These elements can bear on the type and/or length of sentence imposed.

Of particular interest to the court, pertaining to sex offenders, is the individual’s likelihood of reoffending.  Recidivism is a significant concern, since some sex offenders are prone to commit future crimes—and other offenders are very unlikely to do so.  It is not practical for judges to impose lengthy sentences to all felons.  Consequently, they most often wish to know the likelihood of an individual’s recidivism and this data is considered, among other important variables, when assigning sentences.

Forensic psychologists’ sex offender evaluations are based substantially on actuarial data.  Research with sex offenders over many years has shown that certain variables are useful for prediction, within reasonable parameters of course, regarding which individuals are more or less likely to re-offend in the future.  While no prediction is infallible, judges are able to make better informed decisions based on various predictor variables.  Sex offender evaluations are key components to this appraisal process.