The illegality of shipping a "switchblade" across any state line ("int
erstate")is a matter of federal law. There are narrow exceptions, noted below. A common carrier, being merely a conduit, has no exposure. The shipper generally is subject to the law unless, for example, shipping switchblades to comply with a contract with the military.
State and local law is irrelevant to whether a federal felony has been committed.
Intr
astate shipment - within a state - is governed by state and local law.
29 U.S. Code
§1241. Definitions
(a) The term interstate commerce means commerce between any State, Territory, possession of the United States, or the District of Columbia, and any place outside thereof.
(b) The term switchblade knife means any knife having a blade which opens automatically
(1) by hand pressure applied to a button or other device in the handle of the knife, or
(2) by operation of inertia, gravity, or both.
§1242. Introduction, manufacture for introduction, transportation or distribution in interstate commerce; penalty
Whoever knowingly introduces, or manufactures for introduction, into interstate commerce, or transports or distributes in interstate commerce, any switchblade knife, shall be fined not more than $2,000 or imprisoned not more than five years, or both.
(Pub. L. 85623, §2, Aug. 12, 1958, 72 Stat. 562.)
§1244. Exceptions
Sections 1242 and 1243 of this title shall not apply to
(1) any common carrier or contract carrier, with respect to any switchblade knife shipped, transported, or delivered for shipment in interstate commerce in the ordinary course of business;
(2) the manufacture, sale, transportation, distribution, possession, or introduction into interstate commerce, of switchblade knives
pursuant to contract with the Armed Forces;
(3) the Armed Forces or any member or employee thereof
acting in the performance of his duty;
(4) the possession, and transportation upon his person, of any switchblade knife with a blade three inches or less in length by any individual who has only
one arm; or
(5) a knife that contains a spring, detent, or other mechanism designed to create a bias toward closure of the blade and that requires exertion applied to the blade by hand, wrist, or arm to overcome the bias toward closure to assist in opening the knife.