"See, e.g., Hamilton v. Regents of the Univ. of Cal., 293 U.S. 245, 264 (1934) (“The conscientious objector is relieved from the obligation to bear arms in obedience to no constitutional provision, express or implied; but because, and only because, it has accorded with the policy of Congress thus to relieve him.”); United States v. Macintosh, 283 U.S. 605, 624 (1931) (rejecting claim of constitutional right to refrain from military service based on the “well-nigh limitless extent of the war powers”), abrogated in part by Girouard v. United States, 328 U.S. 61 (1946). Lower courts have largely, though not completely, followed this trend. See United States v. Burns, 450 F.2d 44, 46 (10th Cir. 1971); United States v. Boardman, 419 F.2d 110, 112 (1st Cir. 1969); United States v. Crouch, 415 F.2d 425, 430 (5th Cir. 1969); Korte v. United States, 260 F.2d 633, 635 (9th Cir. 1958) (“It is well settled that exemption from military service is a matter of legislative grace and not a matter of right.”"