A defence of risk relative capacity

Sam Boyle1

1School Of Law, Queensland University Of Technology, Brisbane, Australia

Risk relative capacity, the idea that riskier decisions require a higher level of capacity than less risky decisions, is controversial. Significantly, it creates the possibility that a person could have capacity to accept medical treatment, but not to refuse it. However, although risk relative capacity does carry the danger of equating incapacity with treatment refusal, a danger that must be managed, I defend its place in the law of capacity.

Firstly, there is no clear line between capacity and incapacity; legal capacity is a political, legal judgment. While the risk of a decision should never be considered determinative of capacity, it is a legitimate factor that may be taken into account. A number of writers have rejected risk relative capacity, but endorsed giving more scrutiny to capacity in cases of high risk. I argue that this amounts to the same thing, and the justification for more scrutiny of capacity in cases of high risk is the same as that for risk relative capacity.

Secondly, I argue that not testing capacity in cases of low risk decisions is a form of risk relative capacity, and that this practice is a sensible way of determining when capacity should be assessed.

Finally, I argue that if it is used properly, risk relative capacity can actually be a tool for patient empowerment. This is because it ought to challenge doctors to demonstrate the risk of refusing treatment. Moreover, ‘risk’ in medical treatment decisions is not one-directional. There is also a risk involved in the removal of a person’s capacity, and in the provision of unwanted medical treatment. Therefore, risk relative capacity could actually make it more likely for someone refusing treatment to be found to have capacity.


Sam is a lecturer at Queensland University of Technology. He teaches property law, medical law and administrative law. Sam is completing a PhD on the issue of capacity in the case of anorexia nervosa at University of Queensland.