Competency Assessment Instrument

The Competence to Stand Trial Assessment Instrument, often called the Competency Assessment Instrument (CAI), was developed in 1973 as a companion instrument to the Competency Screening Test (CST) and sought to standardize as well as quantify the criteria for competence to stand trial. The instrument was created by an interdisciplinary team of psychologists, psychiatrists, and lawyers at Harvard’s Laboratory of Community Psychiatry during a project funded by a research grant from the Center for Studies of Crime and Delinquency, National Institute of Mental Health. The CAI addresses 13 functions related to the defendant’s “ability to cope with the trial process in an adequately self-protective fashion.”

Although the concept that a defendant must be competent to proceed in the trial process has been generally accepted in Western jurisprudence since the late 1700s, the current standard for competence to stand trial in the United States was laid out by the U.S. Supreme Court in Dusky v. United States in 1960. In Dusky, the Court held that for a defendant to be deemed competent to stand trial, he or she must have “sufficient present ability to consult with his lawyer with a reasonable degree of rational understanding” and “a rational as well as factual understanding of the proceedings against him.”

On the basis of the standard as set forth in Dusky as well as reviews of appellate cases and legal literature, observations of pretrial competence hearings, and interviews of attorneys and judges, the interdisciplinary team conceptualized the standard of competence to stand trial as having three parts: the ability to cooperate with one’s attorney in one’s own defense, awareness and understanding of the nature and object of the legal proceedings, and understanding of the consequences of the proceedings.

As one of the first semistructured measures of trial competency, the CAI influenced the development of nearly every other instrument that has been created for competence to stand trial evaluations. The administration time of the CAI is approximately 1 hour with relatively high functioning defendants. The 13 areas of functioning addressed by the CAI are the following:

  1. Appraisal of available legal defenses
  2. Unmanageable behavior
  3. Quality of relating to attorney
  4. Planning of legal strategy, including guilty pleas to lesser charges where pertinent
  5. Appraisal of the role of persons involved in a trial
  6. Understanding of court procedure
  7. Appreciation of charges
  8. Appreciation of the range and nature of possible penalties
  9. Appraisal of the likely outcome
  10. Capacity to disclose to attorney the available pertinent facts surrounding the offense
  11. Capacity to realistically challenge prosecution witnesses
  12. Capacity to testify relevantly
  13. Self-defeating versus self-serving motivation (legal sense)

In the manual, the 13 functions are conceptually defined with statements, and two or three sample questions accompany each function.

Each functional item on the CAI is to be rated on a five-point Likert-type scale, wherein a score of 1 relates to a total lack of capacity to function and a score of 5 relates to no impairment, or adequate capacity to function. A score of 6 is given when there is insufficient information to score the respective item. The item scores are neither weighted nor summed, but rather are intended to stand alone and assist the evaluator in the formation of his or her subsequent report and potential testimony. The authors of the CAI explicitly set forth the caveat that the CAI is not meant to serve as a predictor of future trial-related abilities, since scores on the instrument may fluctuate over time. The scoring process functions under the assumptions that the defendant will be afforded adequate counsel and the forensic examiner using the CAI possesses a fundamental understanding of the realities of the criminal justice system.

Little is known about the psychometric properties of the CAI. The scoring of the CAI is not standardized, and there are no norms available for the instrument. Interrater reliability coefficients for the instrument have been found to range from .84 to .97 among experienced raters and from .43 to .96 among inexperienced raters. The CAI has been found to correlate with other instruments intended to measure the same abilities as the CAI (i.e., the Competence Screening Test and Interdisciplinary Fitness Interview), lending exiguous evidence in support of its construct validity. Research on the utility of the CAI as a classification or predictive tool is scant as well, but the research that was conducted found that many evaluators used the CAI as a conceptual tool—forgoing the quantification of the items.

Controversies that surrounded the CAI on its publication regarded biases that may be inherent in the scoring of the instrument. Specifically, bias against individuals who do not have confidence in the criminal adjudication process or bias as a result of an evaluator’s assumptions about the dynamics of the circumstances surrounding a trial and attorney performances have been cited. Rebuttal of these criticisms has referred to the fact that the authors have clearly indicated that the scoring of the CAI operates under the presumptions of adequate legal counsel and a trial characterized by a legal standard of fairness. Although the CAI does not include a methodical evaluation of the defendant’s specific trial circumstances, three items (Items 1, 4, and 9) evaluate the defendant’s capacities or perceptions regarding his or her circumstances. However, the CAI manual does not provide any guidelines for characterizing the trial circumstances. The major contribution of the CAI was the delineation of 13 legally pertinent concepts and functional areas, a contribution that continues to influence the development of instruments created to evaluate defendants’ competence to stand trial.


  1. Dusky v. United States, 362 U.S. 402 (1960).
  2. Grisso, T. (2003). Evaluating competencies: Forensic assessments and instruments. New York: Kluwer Academic/Plenum.
  3. Harvard Medical School, Laboratory of Community Psychiatry. (1973). Competence to stand trial and mental illness (DHEW Publication No. [ADM] 77-103). Rockville, MD: NIMH, Department of Health, Education, and Welfare.

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