The medical rights of minors have been questioned, especially due to information on adolescent brain development and studies on adolescent decision-making. This chapter briefly introduces the mature minor doctrine (MMD) and its history, justification, and practice and then presents some of the objections to the MMD. The article then highlights new knowledge about adolescent brain development (ABD) and what this may contribute to this debate and describes "hot cognition" and "cold cognition". It concludes by alerting the reader to the danger of making inappropriate use of the discoveries of brain science and proposing a prudent approach to adolescent consent and confidentiality, one that incorporates the new knowledge on ABD without "turning back the clock" on the medical rights of minors.