I think substitute decision-makers can indeed have a lot of merit. I think what's problematic is that often they don't because they're not up to date in terms of what the patient has expressed in a written or oral directive.
I think that advance care planning is a better way to go, because with advance care planning, at least the wishes and values of the patient are updated, so to speak, on a pretty regular basis so that the substitute decision-maker can really understand the values, attitudes, beliefs, specific requirements and wishes of the person.