Constitutional law assumes that individuals accused of a crime possesses the mental faculties necessary in order to make informed decisions regarding their trials.  Both legal statutes and case law have determined that some individuals are incapable of meaningfully participating in their own defense, if they possess mental defect(s) or disease(s) that create substantial impairment.  Forensic psychologists evaluate accused individuals in order to appraise the likelihood that a potential defect or disease exists—sometimes evaluating the degree that the defect(s) likely affected the individual from knowing right or wrong at the time of the alleged offense (insanity) or whether the individual can meaningfully participate in the defense (competency to stand trial).  This includes the ability to legally appreciate the implications of one’s actions as the defense process unfolds.  Competency evaluations often involve a process of conducting a clinical interview with the individual, psychological testing, extensive record review, contacting collateral sources in the case, and utilizing instruments specifically designed for competency evaluations.