Final answer:
Army policy generally prohibits putting hands in pockets while in uniform as it is seen as unprofessional and against military bearing, though exceptions may apply in certain conditions.
Step-by-step explanation:
The Army policy concerning putting hands in pockets while in uniform is quite clear and strictly enforced. Soldiers are generally discouraged from putting their hands in their pockets because this practice is seen as unprofessional and contrary to military bearing and discipline.
There are practical reasons behind this too, such as the necessity to maintain a uniform appearance and readiness to respond or salute when appropriate. The regulation often referenced for the U.S. Army is Army Regulation 670-1, which sets the standards for wear and appearance of Army uniforms and insignia.
Exceptions may be made in certain circumstances, such as extreme cold weather conditions, but these are situational and typically at the discretion of the commanding officer.