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.
Asymmetry in knowledge and power between (1) physicians and patients and (2) physician educators and their students creates a climate for possible abuse in both sets of relationships.