Predicting Restorability of Incompetent Criminal Defendants

Abstract

U.S. courts frequently require forensic examiners to offer opinions concerning the likelihood that criminal defendants found incompetent to stand trial can have their competence restored through treatment. Yet no jurisdiction has established legal guidelines for testimony concerning restorability, and several authors have suggested that mental health professionals cannot accurately predict whether treatment to restore competence will succeed. This study asked whether reliable information that is consistently available at the time of examination might support empirically grounded opinions about the likelihood of restoration. Using records from all 351 inpatient pretrial defendants who underwent competence restoration at a state psychiatric hospital from 1995 through 1999, I evaluated whether several types of information that are reliable and that could consistently be made available to forensic examiners - including evaluees' demographic characteristics, diagnoses, symptom patterns, criminal charges, number of prior public sector hospitalizations, and cumulative prior length of stay (LOS) - would predict outcome of restoration efforts. I modeled the probability of successful restoration using logistic regression equations, and evaluated the equations' predictive accuracy using k-fold cross-validation and receiver operating characteristic (ROC) analysis. Lower probability of restoration was associated with having a misdemeanor charge, longer cumulative LOS, older age, and diagnoses of mental retardation, schizophrenia, and schizoaffective disorder. Although the overall rate of successful restoration for felony defendants was 75 percent, logistic equations allowed selection of subgroups with high predicted probabilities of restoration (>90%) and low probabilities of restoration (<35%). In cross-validation simulations, predictive equations had ROC areas of 0.727 for all defendants, and 0.735 for felony defendants. These findings provide scientific support for testimony that two types of incompetent evaluees have well-below-average probabilities of being restored: chronically psychotic defendants with histories of lengthy inpatient hospitalizations and defendants whose incompetence stems from irremediable cognitive disorders (such as mental retardation). Nonetheless, courts may still deem low probabilities of success to be substantial enough to warrant attempts at restoration.

Keywords: courts, forensic examiner, criminal defendant, incompetent to stand trial, competence restoration, prediction, logistic regression, probability, schizophrenia, mental retardation, cross-validation, expert opinion, testimony

JEL Classification: C00, I00, K14