When convicted of a courts martial an officer is not reduced in grade and cannot be demoted to the enlisted ranks. Since the officer's commission (and rank) is the result of an act of Congress, no Courts Martial can remove it. Even if convicted of a major crime under the UCMJ, confined for live, forfeiture of all pay and allowances, and dismissal from the service, no officer's rank can be reduced.
Half True---
When convicted of a courts martial an officer is not reduced in grade and cannot be demoted to the enlisted ranks. Since the officer's commission (and rank) is the result of an act of Congress, no Courts Martial can remove it. Even if convicted of a major crime under the UCMJ, confined for live, forfeiture of all pay and allowances, and dismissal from the service, no officer's rank can be reduced. ----Half true
U.S.C. Title 10 Subtitle A-General Military Law, Part 1-Organization and General Military Powers have the statutes specific to the authority to appoint commissioned officers in the military services. Appointment of officers in the commissioned grades is made by the president with authority to appoint delegated to each service secretary. See sections 64, 12203, 12213, 12214 and others.
Subtitle E, Part II, chapter 1207, section 12241 Appointments of warrant officer is made by the pleasure of the secretary concerned.
Rule 1003 Punishments (8) © Limits on Punishment
Only a general court-martial, upon conviction of any offense in violation of the code, may sentence a commissioned officer or commissioned warrant officer or a cadet or midshipman to be separated from the service with a punitive separation. In the case of commissioned officers, cadets, midshipmen, and commissioned warrant officers, the separation shall be dismissal. In the case of all other warrant officers, the separation shall be by dishonorable discharge.
Rule 1003 Punishments (8) (A) Punitive Separations
Dismissal. Dismissal applies only to commissioned officers, commissioned warrant officers, cadets, and midshipmen and may be adjudged only by a general court-martial. Regardless of the maximum punishment specified for an offense in Part IV of this manual, a dismissal may be adjudged for any offense of which a commissioned officer, commissioned warrant officer, cadet, or midshipman has been found guilty.
(i) A commissioned or warrant officer or a cadet, or midshipman may not be reduced in grade by any court-martial. However, in time of war or national emergency the Secretary concerned, or such Under Secretary or Assistant Secretary as may be designated by the Secretary concerned, may commute a sentence of dismissal to reduction to any enlisted grade.
FYI—during a reduction in Force a commissioned officer can volunteer option to be reduced to an enlisted grade.