The relationship between the MMSE as a measure of cognitive deficit and two procedures for assessing medical-legal competence is explored. The findings on 60 patients assessed for financial capacity by a multidisciplinary panel, and 41 published cases assessed using the HCAT for capacity to consent to treatment are analysed using logistic regression and ROC curves based on the binary outcome capable/incapable. Cognitive deficit is not a good indicator of the results for mental capacity obtained either by the multidisciplinary panel or the HCAT. The relationship between cognitive deficits and procedures for the allocation of decisional authority is unclear. Some discussion is given to account for this discrepancy.
