• Pioneering forensic instrument

  • Widely used in courts throughout the United States

This standardized instrument assesses competence to stand trial for persons with intellectual disability. Based on criteria in the U. S. Supreme Court case of Dusky v. United States, the CAST*ID® has separate sections for Basic Legal Concepts, Skills to Assist Defense, and Understanding Case Events.

The examiner reads aloud each question and records the client's response in a booklet. A reusable Subject Form allows the client to follow along as the examiner reads the questions. The test is normed for adolescents and adults with mild and moderate levels of severity of intellectual disability.

Two analyses of vocabulary and syntax found readability to be at a fourth grade level or less.

Normative studies showed a high degree of internal reliability (Cronbach's alpha coefficient of .92), excellent test-retest reliability (Pearson product moment coefficient of .92), and good interscorer reliability for the open-ended questions (80 - 90 percent).

Face Validity
A panel of expert criminal disability lawyers rated the items and the format favorably.

Criterion Validity
Two independent studies found significantly higher CAST*ID® total scores for criminal defendants with intellectual disability who were competent to stand trial versus those who were incompetent. These findings provided replicated evidence for satisfactory criterion validity and were cited in a favorable review of the CAST*ID® by Deborah K. Cooper, Ph.D. and Thomas Grisso, Ph.D. in Behavioral Sciences and the Law, 15, 347-364 (1997).

Caroline T. Everington, Ph.D. was Associate Dean and Professor, College of Education, Winthrop University. Her work was cited in the majority opinion in the 2002 U. S. Supreme Court landmark case banning the death penalty for defendants with intellectual disability, Atkins v. Virginia.

Ruth Luckasson, JD, is a distinguished professor of special education at the University of New Mexico, where she also has been the Chair of the Department of Special Education. Previously, she was president of the American Association on Intellectual and Developmental Disabilities. She currently serves on The Arc of the United States Policy and Positions Committee and as chair of its Legal Advocacy and Human Rights Subcommittee.

Ages: The CAST*ID® is normed for adolescents and adults ages 18 and older with a mild or moderate level of severity of intellectual disability.

Length: The instrument typically takes about 30 - 45 minutes to administer.

Qualified Users: Licensed or registered psychologists, psychiatrists, lawyers, or special educators with at least one course in psychometric testing from an accredited institution of higher education and at least one year of successful professional experience working with people with intellectual disability.

Pricing: (PDF file, Word file).