NASA Final Rule: 14 CFR Part 1214: Space Flight, Federal Register
Keith's note: These rules apparently only apply to Orion (and SLS). No mention is made as to who is in charge aboard Dragon or Starliner (or other commercial vehicles) when NASA people are on board. That said, the take home message: no fist fights on the bridge.
"Sec. 1214.702 Authority and responsibility of the NASA Commander.
(a) During all flight phases, the NASA Commander shall have the absolute authority to take whatever action is in his/her discretion necessary to:
(1) Enhance order and discipline.
(2) Provide for the safety and well-being of all personnel on board.
(3) Provide for the protection of the spacecraft and payloads. The NASA Commander shall have authority, throughout the mission, to use any reasonable and necessary means, including the use of physical force, to achieve this end.
(b) The authority of the NASA Commander extends to any and all personnel on board the spacecraft including Federal officers and employees and all other persons whether or not they are U.S. nationals.
(c) The authority of the NASA Commander extends to all spaceflight elements, payloads, and activities originating with or defined to be a part of the NASA mission.
(d) The NASA Commander may, when he/she deems such action to be necessary for the safety of the spacecraft and personnel on board, subject any of the personnel on board to such restraint as the circumstances require until such time as delivery of such individual or individuals to the proper authorities is possible.
Sec. 1214.703 Chain of command.
(a) The NASA Commander is a trained NASA astronaut who has been designated to serve as commander on a NASA mission and who shall have the authority described in Sec. 1214.702 of this part. Under normal flight conditions (other than emergencies or when otherwise designated) the NASA Commander is responsible to the Mission Flight Director.
(b) Before each flight, the other flight crewmembers will be designated in the order in which they will assume the authority of the NASA Commander under this subpart in the event that the NASA Commander is not able to carry out his/her duties.
(c) The determinations, if any, that a crewmember in the chain of command is not able to carry out his or her command duties and is, therefore, to be relieved of command, and that another crewmember in the chain of command is to succeed to the authority of the NASA Commander, will be made by the NASA Administrator or his/her designee.
Sec. 1214.704 Violations.
(a) All personnel on board the NASA mission are subject to the authority of the NASA Commander and shall conform to his/her orders and direction as authorized by this subpart.
(b) This subpart is a regulation within the meaning of 18 U.S.C. 799, and whoever willfully violates, attempts to violate, or conspires to violate any provision of this subpart or any order or direction issued under this subpart shall be subject to fines and imprisonment, as specified by law."
Keith's note: According to 18 U.S. Code § 799 if you break the NASA rules you "shall be fined under this title, or imprisoned not more than one year, or both". In other words the fine is (apparently) TBD and the longest you can sit in the brig for punching your captain is a year.