Now you see it, now you don't; consent and the legal protection of autonomy.

In this paper I describe the piecemeal development of the law regarding capacity to consent to treatment. I note how the requirement has changed from Justice Cardozo's low-level requirement of a 'sound mind' to the relatively high-level Re C test. I discuss the limitations of the Re C test. Particularly, that the requirements from believing information and ability to weigh information in the balance--which should be applied to the patient's ability to decide and not the actual treatment decision--are open to subjective abuse and the risk of abductive inferences made from the patient's actual decision. I suggest that, because of a generally poor standard of reasoning ability, only a minimal level of rationality should be required. Furthermore, I demonstrate the fallacy of the judicially approved risk related standard and discuss the Catch-22 situation that arises when it is implemented.