Competence by consequence: ambiguity and incoherence in the law.

There is an ambiguity of principle delivered by those legal judgements which have considered the issue of whether the level of patients' decision-making capacity should vary in accordance with the seriousness of risks associated with the procedure subject to decision, particularly in decisions to refuse life-saving treatment. There appears to be support for (1) a risk-related standard of capacity, although some judgements could also be interpreted as (2) a procedural standard, subject to a rigorous standard of evidence of capacity. I argue that a risk-related standard of capacity itself is incoherent. This would lend weight to the second interpretation. However, I argue that the wording of the judgements belies an allegiance to the first interpretation, which is also consistent with how medical practitioners generally view capacity in these situations. I consider the implications of the dissonance between the two ways of interpreting the judgments, and make suggestions aimed at clarifying the issue of risk-related competence for clinicians.