For proxy decisions to carry the same weight as those made contemporaneously by patients, they must meet a criterion of normative authority. The substituted judgement standard identifies normative authority with accuracy: proxy decisions should accurately replicate the decision the patient would have made under the circumstances were they competent (Buchanan and Brock 1992). However, studies have consistently demonstrated that proxies are only accurate around 68% of the time (Shalowitz, Garrett-Mayer, and Wendler 2006). Indeed, even after proxies have engaged in focused discussions with patients regarding their wishes, proxy accuracy does not significantly improve (Bravo, Sene, and Arcand 2018). This has motivated some commentators to suggest that we should either ditch proxy decision-making in favour of advance directives, or simply act in line with the patient’s best medical interests.
I suggest that falling back on these options is unnecessary. Instead of requiring that proxies accurately replicate patient wishes, I argue that they should make value congruent decisions. My position is that a proxy’s decision carries normative authority insofar as it reflects what the patient values, and that this is the case even if it fails to replicate exactly what the patient would have chosen. I end by noting that insofar as value congruence ought to be the aim of proxy decision-making, the current model of proxy appointments is inadequate. As I will show, proxies should be appointed because they share key medically relevant values with the patient. This value-sharing confers the kind of epistemic access required to produce value congruent decisions.