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Voyager chief medical officer

The original CMO of USS Voyager

The chief medical officer (CMO), first medical officer, senior medical officer, ship's physician, or ship's surgeon was senior staff-level medical practitioner with medical authority who was, by definition, "in command of medicine on [their assigned posting]." (TOS: "Turnabout Intruder")

A nurse could also hold this position if no qualified doctors were available. (TAS: "The Lorelei Signal")

Typical ranks[]

Chief medical officers have held a variety of ranks. They could hold any rank from lieutenant junior grade to lieutenant commander. (DS9: "Emissary"; TOS: "Court Martial")

Chief medical officers were eligible to take the Bridge Officer's Test for promotion to full commander, which was not required for their CMO position. At this point, they were considered capable of assuming command of a starship. (TNG: "Descent", "Descent, Part II", "Thine Own Self")

Specific duties[]

Chief medical officers aboard a starship or starbase were directly in charge of the sickbay or infirmary, commanding Medical department personnel and activities. The CMOs' primary duties were the oversight and maintenance of the overall health, physical, and mental fitness of crew and passengers. (TOS: "The Corbomite Maneuver", "Charlie X") Furthermore as standard medical procedure, the CMO had full medical authority over any patient officially admitted into their care in their facility, including superior officers, until they were formally released from care. (TOS: "Turnabout Intruder"; VOY: "Ex Post Facto")

Officers likely to be assigned as the CMO over long-duration missions of exploration had scientific training in disciplines outside of medicine, allowing them to take on major, extended research projects, or to better participate in a wider variety of encounters. (TOS: "The Immunity Syndrome"; TNG: "Clues", "Suspicions"; DS9: "Explorers")

Medical authority[]

According to Starfleet's handbook on personal relationships, "All Starfleet personnel must obtain authorization from their CO, as well as clearance from their Medical Officer, before initiating an intimate relationship (or intimate relations) with an alien species." Such a waiver also required the captain's approval. (VOY: "The Disease", "Prophecy")

In addition to the normal duties of an officer, Starfleet Order 104, Section C gave CMOs the power to relieve an officer or crewman, including a superior one of their duties if in the CMO's professional judgment, the officer in question was medically unfit. The CMO in question would need to officially certify and provide evidence of unfitness at a subsequent board of inquiry. (ENT: "Hatchery"; TOS: "The Doomsday Machine") Typically, the CMO was expected to have the support of a senior command officer or detailed medical documentation to justify this course of action. Geordi La Forge noted that this could blow back on the CMO in question if they used this power to remove a captain who was later found to not have become unfit. (TOS: "The Doomsday Machine"; TNG: "Lonely Among Us"; VOY: "Year of Hell, Part II")

The chief medical officer was able to impose medical physicals upon crewmembers if the mission lasted more than two weeks. (VOY: "Memorial")

The CMO also seemed to have the authority to order officers to do things that would be beneficent to their health, like sleeping. (TNG: "Violations")

In the 23rd century, chief medical officers certified the health of research personnel on alien planets on a yearly interval. (TOS: "The Man Trap")

In an alternate timeline on stardate 51425, The Doctor cited Starfleet Medical Regulation 121, Section A in an attempt to relieve Captain Kathryn Janeway of her command. She refused his order, stating that he had no way to actually "implement this protocol". He countered, by saying that he would note the incident in his official log, and that it could lead to her general court martial. (VOY: "Year of Hell, Part II")

List of chief medical officers[]


Alternate timelines and parallel universes[]


See also[]


External link[]