 The right of the patient to exercise autonomy, whether to accept the recommendation of physician is not lost when the patient is unable to make health related decision. This is the basis of substituted judgment. Without written advance directives, a surrogate has to be assigned using relevant state relationship hierarchy, and usually a family member serves as a surrogate when the patient no longer has capacity to make medical decisions. Several studies showed that surrogates do not predict the patients preference accurately when both are asked to respond to hypothetical questions. Patient designated hierarchy predicted the patient treatment preferences with 69 accuracy whereas legally assigned proxy was accurate in 68. Even the prior discussion of the treatment preferences did not seem to improve the surrogate accuracy. Surrogates make errors predicting patients preferences in different directions, as was found in several studies. Three studies have found that surrogates err by providing intervention that patients do not want, while others found no specific trends. Other studies showed physicians to be less accurate than surrogates in predicting the patients wishes. 