Competency to stand trial (CST) determinations require an adherence to legal adjudication standards and psychological assessments methods. However, the forensic decision making on these matters is fraught with complex and enduring dilemmas. Questions persist about the vague and ambiguous nature of the precedent-setting U.S. Supreme Court case law on mental illness and competency as applied to particular defendants. In addition, the clinical evaluation procedures pose sufficient validity and reliability problems that the assessment instruments themselves have been the source of considerable consternation. As a result, the medicolegal system, on occasion, has allowed controversial and profoundly disturbed mental health defendants to pro se their cases (e.g., Colin Ferguson) and/or has rendered questionable psychological screenings for high-profile CST cases (e.g., Theodore Kaczynski). In this article, the authors revisit the legal and psychological pitfalls attributable to the CST determination. They examin...