The enactment of a single legislative scheme governing nonconsensual treatment of both 'physical' and 'mental' illnesses, based on incapacity principles, has been mooted in recent law reform debates in the UK. We propose a framework for such legislation and consider in more detail the provisions it should contain. The design of legislation that combines the strengths of both incapacity and civil commitment schemes can be readily imagined, based on the criteria for intervention in England and Wales found in the Mental Capacity Act 2005. Such legislation would reduce unjustified legal discrimination against mentally disordered persons and apply consistent ethical principles across medical law.