Due process requires that a defendant be competent to stand trial, which includes capacity to assist counsel and to understand the nature of the proceeding sufficiently to participate in and make decisions about rights afforded to defendants.
There are several acceptable approaches for performance of competency to stand trial evaluations including standardized methods such as state competency tests. Traditionally, a full-fledged assessment involves a clinical interview, a mental status exam, a psychological test, and a social history, but the modern trend is to rely upon an interview and/or a psychological test. There are a number of psychological tests available in standardized and local variations. Many evaluators use clinical measures of personality and intelligence, such as thestandardized test MMPI-2.