10 U.S.C. § 9229
Command: commissioned officers in certain designated categories
An officer designated as a medical, dental, veterinary, medical service, or biomedical sciences officer or as a nurse is not entitled to exercise command because of rank, except within the categories prescribed in subsection (a), (b), (c), (d), (e), (f), or (i) of section 9067 of this title, or over persons placed under his charge.