Advance directives, substituted judgment, and the best-interest standard all have limitations that constrain their usefulness in making medical decisions for patients who cannot choose for themselves.
The practice of banking sperm from adolescents about to undergo chemotherapy is not universal, which lends support to the argument that parental consent be required for the intervention.
Advance directives do not always resolve questions about the best care for patients who no longer have decision-making capacity; physicians and patient surrogates can take alternative approaches to arrive at the best care decision.