Any person subject to this chapter who, while in the hands of the enemy in time of war—

(1) for the purpose of securing favorable treatment by his captors acts without proper authority in a manner contrary to law, custom, or regulation, to the detriment of others of whatever nationality held by the enemy as civilian or military prisoners; or

(2) while in a position of authority over such persons maltreats them without justifiable cause;

shall be punished as a court-martial may direct.