47 USC 324
47 USC 324
§ 324 - Use of minimum power
CHAPTER 5— WIRE OR RADIO COMMUNICATION › SUBCHAPTER III— SPECIAL PROVISIONS RELATING TO RADIO
In all circumstances, except in case of radio communications or signals relating to vessels in distress, all radio stations, including those owned and operated by the United States, shall use the minimum amount of power necessary to carry out the communication desired.