The importation of switchblade knives is permitted by 15 U.S.C. 1244, when:

(a) Imported pursuant to contract with a branch of the Armed Forces of the United States;

(b) Imported by a branch of the Armed Forces of the United States or any member or employee thereof acting in the performance of his duty; or

(c) A switchblade knife, other than a ballistic knife, having a blade not exceeding 3 inches in length is in the possession of and is being transported on the person of an individual who has only one arm.

[T.D. 71-243, 36 FR 18860, Sept. 23, 1971, as amended by T.D. 90-50, 55 FR 28192, July 10, 1990]