US Flag Code Title 4, Chapter 1, Sec. 4 dictates the flag should be saluted in the following manner:
"The Pledge of Allegiance to the Flag [referenced above] should be rendered by standing at attention facing the flag with the right hand over the heart. When not in uniform men should remove their headdress with their right hand and hold it at the left shoulder, the hand being over the heart. Persons in uniform should remain silent, face the flag, and render the military salute. (Added Pub. L. 105-225, Sec. 2(a), Aug. 12, 1998, 112 Stat. 1494.)"
US Flag Code Title 4, Chapter 1, Sec. 10, in effect as of Jan. 20, 2004, gives the President of the United States the authority to change the US Flag Code:
"Any rule or custom pertaining to the display of the flag of the United States of America, set forth herein, may be altered, modified, or repealed, or additional rules with respect thereto may be prescribed, by the Commander in Chief of the Armed Forces of the United States, whenever he deems it to be appropriate or desirable; and any such alteration or additional rule shall be set forth in a proclamation. (Added Pub. L. 105-225, Sec. 2(a), Aug. 12, 1998, 112 Stat. 1498.)"