Proper diagnosis of intellectual disability (ID) in criminal justice systems is critical to the delivery of fair justice. However, traditional practices that rely on a single Full-Scale IQ (FSIQ) cutoff often lead to diagnostic discrepancies. This paper discusses how Cattell Horn Carroll theory of cognitive abilities is used as a multidimensional measure of the ID in justice-involved people. The issue is that the defendants may be under identified or misclassified when assessment procedures focus on global IQ scores without detailed examination and testing of broad cognitive domains and adaptive functioning. The sample of 214 defendants referred from four correctional facilities was used in a cross-sectional study that included a forensic psychological assessment. The participants were administered CHC-congruent cognitive tests of fluid reasoning (Gf), crystallized intelligence (Gc), working memory (Gwm), processing speed (Gs), and visual-spatial processing (Gv), in addition to the standardized adaptive behavior scales. The CHC model structure was supported by confirmatory factor analysis (CFI = 0.95; TLI = 0.93; RMSEA = 0.048). According to conventional FSIQ ≤ 70 criteria, 21.0% of study participants met diagnostic thresholds for ID. Nevertheless, the 29.4% rate of fulfilling comprehensive diagnostic criteria when CHC domain deficits and adaptive impairments were combined into a single domain showed an 8.4% increase in cases identified. The logistic regression analysis showed that using CHC broad ability indices increased classification accuracy from 78.6 to 88.9. Findings indicate that CHC-based assessment has greater diagnostic sensitivity and provides a more comprehensive cognitive picture, useful for forensic decision-making. The study concludes that multidimensional CHC-informed assessments are more precise, clinically and legally defensible, and that their inclusion in standard assessment programs should be promoted in criminal justice systems