Correlates of defendants found incompetent to stand trial and second generation competency measures: A meta-analytic review

A meta-analysis of 13 studies that examined the characteristics of competent and incompetent criminal defendants (N = 2062) was conducted to synthesize the current data on the second generation competency measures, the MacCAT-CA and the ECST-R. Effect sizes reflecting the size of the relationship between competency status and defendant characteristics were computed and averaged. The defendant characteristics most strongly related to incompetency were poor performance on the competency instruments and evidence of psychosis. Unlike previously studied competency measures, the MacCAT-CA and ECST-R provide scales that roughly correspond to a 3-pronged model of competency based on the Dusky standard. Analysis of individual scales revealed that performance on specific prongs relates differently to various symptom presentations as well as estimates of IQ. Limitations of existing research include a lack of research on well-defined ethnic groups, the absence of a gold standard with which to validate competency instruments, leaving competency instruments to be validated on groups with questionable validity, and scant research on personality disorders and competency. Limitations of this study include small sample size and a heavy reliance on a combination of small, unpublished studies and large studies used in the initial validation studies for each of the instruments. Despite providing a structured approach with strong psychometric properties, the MacCAT-CA and the ECST-R remain underused. Directions for future research include (a) creating an understanding of the barriers to the practical application of these tools which may allow for more effective competency assessment in the future and (b) studying the performance of various ethnic groups on each of these measures and attempting to help clinicians understand how cultural difference may impact competency to stand trial.