Officer

In a military service, a commission is an order from the service's supreme authority, such as its commander-in-chief, authorizing an individual to lawfully hold a military rank, with all the privileges and responsibilities of said rank. A commission usually appoints an individual to hold an officer's rank.

Commissions have long been used by the supreme authorities of military services throughout history to appoint officers. In the United States military, for example, commissions were granted by the President of the United States, who was the US military's Commander-in-Chief.

In the Federation Starfleet, commissions were granted by the President of the Federation, the supreme commander of all Federation Starfleet forces.

Temporary, or field commissions, could be granted to officers, appointing them to a higher rank if deemed neccesary, for example, to replace an incapacitated or killed commanding officer in a military confrontation. William T. Riker, for example, was granted a field commission of Captain and given command of the USS Enterprise-D when the ship's commanding officer,Captain Jean-Luc Picard, was abducted and assimilated by the Borg (TNG: "The Best of Both Worlds").

In situations where contact with Starfleet is not possible for very extended periods, a commanding officer has the authority to grant commissions to officers under his or her command, or revoke them. Good examples of this are when Kathryn Janeway, commanding officer of the USS Voyager, promoted her Chief Tactical Officer and Security Chief, Lieutenant Tuvok, to the higher rank of Lieutenant Commander, or when she demoted her Flight Controller, Lieutenant Junior Grade Thomas E. Paris, to Ensign (VOY: "Revulsion", VOY: "Thirty Days").