What Should I, as a Forensic Psychologist Testifying in Criminal Court, Understand About the Dusky Standard?

At its core, the Dusky standard establishes a constitutional minimum for adjudicative competence. The Supreme Court held that a defendant may not be tried unless they possess (1) a sufficient present ability to consult with counsel with a reasonable degree of rational understanding and (2) a rational as well as factual understanding of the proceedings against them.

In criminal court, confusion often arises when the Dusky standard is conflated with the mere presence or absence of mental illness or cognitive impairment. Some assume that a serious psychiatric diagnosis automatically renders a defendant incompetent, while others presume that the lack of a diagnosis confirms competence. Both assumptions miss the point. Dusky is not a diagnostic test but a constitutional safeguard. It asks whether, at the present time, the defendant has the functional ability to understand the proceedings and meaningfully assist counsel. Many individuals with mental illness are fully competent to stand trial, and the law presumes their participation unless that functional threshold is not met. At the same time, proceeding against a defendant who lacks this capacity undermines due process and risks turning the legal process into a formality rather than a fair adjudication. Proper application of Dusky preserves the integrity of the courts by ensuring that trials are conducted only when defendants can participate in their own defense in a constitutionally meaningful way.

For example, a defendant with chronic schizophrenia may demonstrate an intact ability to rationally consult with counsel when symptoms are well managed, while another individual with no formal diagnosis may be unable to engage in reasoned decision-making due to severe anxiety, paranoia, intellectual disability, or cognitive rigidity. As forensic psychologists, our task when conducting competency evaluations is not to determine whether a defendant is mentally ill, but whether, due to any mental, cognitive, or neurological impairment, they possess the present ability to understand the proceedings and meaningfully assist counsel. Conflating diagnosis with competency is one of the most common and most consequential sources of vulnerability in court.

Although the language of Dusky from Dusky v. United States (1960) has remained the same since 1960, its application has evolved substantially through subsequent case law, statutory refinement, and courtroom practice. T For example, Drope v. Missouri confirmed that competency is dynamic and must be reassessed as a defendant’s mental condition changes, while Godinez v. Moran clarified that the standard concerns functional capacity, not the wisdom of a defendant’s choices. Later, Indiana v. Edwards recognized that competency is not unitary, allowing higher functional thresholds for self-representation than for standing trial with counsel.

In parallel, state statutes and professional guidelines have increasingly required evaluators to move beyond conclusory opinions and instead articulate how specific psychological symptoms translate into deficits in discrete legal abilities. As a result, Courts no longer accept evaluations that merely restate the standard or rely on broad diagnostic conclusions. Instead, the crux of modern competency analysis is the nexus between psychological symptoms and functional legal deficits. Forensic opinions must explain how specific symptoms interfere with discrete competencies required in criminal proceedings, including the ability to understand, reason with counsel, or make informed legal decisions. It is this symptom-to-deficit linkage, rather than the presence of a diagnosis alone, that determines whether a defendant meets the Dusky standard.

In practice, this means shifting the focus from abstract clinical constructs to observable, legally relevant behavior. Courts are far less interested in whether a defendant can define legal terms than whether they can apply that knowledge in real decision-making contexts. For example, a defendant may correctly identify the roles of the judge, prosecutor, and defense attorney, yet remain unable to weigh plea options rationally due to fixed delusional beliefs about conspiracy or punishment.

As criminal court experts, we are expected to explain how symptoms interfere with the quality of the attorney–client consultation, the defendant’s ability to engage in rational decision-making, and their ability to maintain reasonable judgment under stress. Simply noting that a defendant “knows their charges” is insufficient if that understanding cannot be integrated into meaningful participation in the defense. Courts expect us to demonstrate this linkage clearly and concretely.

Misapplication of the Dusky standard is a frequent point of attack during cross-examination, particularly when expert testimony blurs the boundary between clinical observation and the legal threshold for competence. One of the most common errors is equating factual knowledge with competence, as though the ability to recite information were sufficient to satisfy Dusky’s requirements.

Opposing counsel may emphasize that a defendant can name the charges, identify courtroom actors, or describe potential penalties and argue that this alone establishes competence. Dusky, however, requires more than factual awareness. It demands both a factual and rational understanding of the proceedings, as well as the capacity to consult with counsel in a reasoned manner. A defendant may accurately repeat legal facts yet remain incompetent if psychiatric symptoms interfere with the ability to use that information coherently or apply it to their own case. For example, a defendant may correctly state the charge and possible sentence but simultaneously hold fixed delusional beliefs that counsel is part of a conspiracy or that the trial is a predetermined sham. In such circumstances, factual understanding is intact, but rational understanding is compromised, rendering the defendant unable to meaningfully assist in the defense despite surface-level legal knowledge.

Other vulnerabilities include over-reliance on diagnostic severity, intellectual functioning, or test scores as proxies for competence. Courts do not ask whether a defendant has a serious mental illness or a low IQ; they ask whether that condition interferes with the defendant’s ability to participate meaningfully in their defense. Testimony that fails to articulate this symptom-to-function nexus—and instead collapses diagnosis, cognition, and competence into a single conclusion—is particularly susceptible to effective cross-examination.

Cross-examination often targets the inherent judgment involved in competency evaluations. We should expect questions such as, “Where exactly does Dusky define ‘rational’?” or “Isn’t this just your opinion?” Effective testimony requires acknowledging that professional judgment is involved while emphasizing that this judgment is structured, evidence-based, and grounded in observed functioning and established legal standards.

Credibility in criminal court is cumulative and fragile. We protect it by ensuring consistency between assessment methods, legal standards, and testimony. This includes using precise legal language accurately, avoiding conclusory statements, and openly acknowledging limitations or uncertainty where they exist. Courts are often more persuaded by transparency than by unwarranted certainty.

For example, precise legal language means stating that a defendant “lacks the present ability to consult with counsel in a rational manner,” rather than opining broadly that the defendant is “too psychotic to stand trial.” Avoiding conclusory statements requires explaining how symptoms interfere with specific legal abilities, rather than asserting that a defendant is incompetent “due to schizophrenia” or “because testing showed low cognitive functioning.” Similarly, consistency in assessment methods means tying interview observations, collateral records, and test findings directly to Dusky criteria, rather than presenting disconnected data points that do not inform the legal question. Finally, acknowledging limitations may involve stating that a defendant’s presentation fluctuated across interviews, that certain legal capacities could not be fully assessed due to noncooperation, or that conclusions are provisional and contingent on current symptom stability. In practice, courts often find such candor more credible than opinions that overstate certainty or ignore evidentiary gaps.

Gray-area cases, where competence is partial, fluctuating, or context-dependent, require particular care. In these cases, our role is not to resolve legal ambiguity but to describe functional strengths and limitations with precision, allowing the court to make the ultimate determination. When we demonstrate neutrality, restraint, and clarity, our testimony is more resilient under adversarial scrutiny.

Forensic psychologists specializing in criminal court work cannot treat Dusky as background knowledge. It is the lens through which CST evaluations are evaluated, challenged, and accepted. Mastery of the standard enables me to conduct more focused assessments, write clearer and more legally relevant reports, and withstand adversarial cross-examination without defensiveness or overreach.

Ultimately, Dusky is not merely a citation; it is a living legal doctrine that demands functional analysis, legal fluency, and professional restraint. When we apply it thoughtfully and testify with clarity and humility, we strengthen both the quality of our evaluations and our credibility as an expert witness. In an era of increasing scrutiny of forensic testimony, mastery of the Dusky standard is not optional; it is foundational to competent and defensible criminal court practice.

Training

• Criminal Forensic Assessment Certificate
  
• Competencies in the Criminal Process
• Case Law Series: Competence to Stand Trial
  
• Best Practices in Competence to Stand Trial
• Advanced Topics in Competency Assessment – Part 1
• Advanced Topics in the Assessment of Competency to Stand Trial – Part 2
• Advanced Topics in the Assessment of Competency to Stand Trial – Part 3
• Assessment of Defendants’ Competency for Self-Representation
• Evidence for Mental Health Professionals
• Evidence for Forensic Mental Health Professionals

Blog Posts

• Attorneys’ Perspectives on Clients’ Abilities to Plead Guilty
• Ensuring Consistency in Forensic Competency Evaluations
• When Attorneys Fail to Clarify Ambiguous Testimony
• Counselors in the Courtroom: Surviving and Thriving in Court Testimony