Final answer:
The President of the United States and the United States Court of Appeals for the Armed Forces are responsible for the overall supervision and administration of military justice in the Army.
Step-by-step explanation:
The overall supervision and administration of military justice in the Army is the responsibility of the President of the United States. According to Section 2 of the Constitution, the President serves as the Commander in Chief of the Army and has the power to require the opinion of the principal officers in the executive departments. The President also has the authority to grant reprieves and pardons for offenses against the United States, except in cases of impeachment.
Additionally, there is the United States Court of Appeals for the Armed Forces (CAAF), formerly known as the United States Court of Military Appeals, which oversees military justice at a higher level. The CAAF is an independent judicial body responsible for reviewing military court-martial cases.
Overall, the President and the United States Court of Appeals for the Armed Forces are the key authorities responsible for the supervision and administration of military justice in the Army.