The entire deaf prison population in the state of Texas formed the basis for this research. The linguistic skills of prison inmates were assessed using the following measures: (1) Kannapell's categories of bilingualism, (2) adaptation of the diagnostic criteria for Primitive Personality Disorder, (3) reading scores on the Test of Adult Basic Education, and (4) an evaluation of sign language use and skills by a certified sign language interpreter who had worked with deaf inmates for the past 17 years. Deaf inmates with reading scores below the federal standard for literacy (grade level 2.9) were the group most likely to demonstrate linguistic incompetence to stand trial, meaning that they probably lacked the ability to understand the charges against them and/or were unable to participate in their own defenses. Based on the language abilities and reading scores of this population, up to 50% of deaf state prison inmates may not have received due process throughout their arrest and adjudication. Despite their adjudicative and/or linguistic incompetence, these individuals were convicted in many cases, possibly violating their constitutional rights and their rights under the Americans with Disabilities Act.