The petitioner, Daniel Jay Schacht, was indicted in a United States District Court for violating 18 U. S. C. § 702, which makes it a crime for any person "without authority [to wear] the uniform or a distinctive part thereof . . . of any of the armed forces of the United States . . . ."^[1] He was tried and convicted by a jury, and on February 29, 1968, he was sentenced to pay a fine of $250 and to serve a six-month prison term, the maximum sentence allowable under 18 U. S. C. § 702. There is no doubt that Schacht did wear distinctive parts of the uniform of the United States Army^[2] and that he was not a member of the Armed Forces. He has defended his conduct since the beginning, however, on the ground that he was authorized to wear the uniform by an Act of Congress, 10 U. S. C. § 772 (f), which provides as follows: