<p>This study employs Kane’s argument-based validation framework to evaluate the CATTI for the English-Chinese language pair. By analyzing the four key inferences—scoring, generalization, extrapolation, and decision rules—within a structured validation of claims, warrants, and rebuttals, this study transcends the fragmented collection of validity evidence and offers a coherent evaluation of the exam’s strengths and limitations. The findings indicate that while the CATTI demonstrates strengths in scoring and generalization supported by standardized rating procedures, systematic rater training and monitoring, stable administration, and consistent test design, significant threats compromise its extrapolation inference and decision rules. The extrapolation inference is increasingly compromised by construct underrepresentation, particularly the lack of assessment of modern instrumental sub-competence and the limited integration of psycho-physiological components, thereby constraining the exam’s alignment with real-world translation demands. Consequently, decision rules, though partially warranted by policy-driven cut-score adjustments for fairness, are constrained by an insufficient extrapolation foundation and a lack of consequences research utilizing empirically grounded and longitudinal designs. Enhancing the validity of CATTI entails administrative adherence to the stipulated syllabus and the incorporation of tasks addressing instrumental sub-competence and psycho-physiological components. Research implications involve employing empirically grounded longitudinal designs across career tracking, workplace observation, job performance comparisons, and washback studies, thereby providing evidence of the exam’s impact on education, training, and career advancement to iteratively refine the test and its decision rules.</p>