<P> Under the Switchblade Knife Act of 1958 (amended 1986, codified at 15 U.S.C. § § 1241--1245), switchblades and ballistic knives are banned from interstate shipment, sale, or importation, or possession within the following: any territory or possession of the United States, i.e. land belonging to the U.S. federal government; Indian lands (as defined in section 1151 of title 18); and areas within the maritime or territorial jurisdiction of the federal government, with the exception of federal, state law enforcement agencies and the military . In addition, federal laws may prohibit the possession or carrying of any knife on certain federal properties such as courthouses or military installations . U.S. federal laws on switchblades do not apply to the possession or sale of switchblade knives within a state's boundaries; the latter is regulated by the laws of that particular state, if any . </P> <P> Occasional disputes over what constitutes a switchblade knife under federal law has occasionally resulted in U.S. Customs seizures of knives from U.S. importers or manufacturers . In one case the seizure of a shipment of Columbia River Knife & Tool knives resulted in an estimated US $1 million loss to the company before the shipment was released . </P> <P> Amendment 1447 to the Switchblade Knife Act (15 U.S.C. § 1244), signed into law as part of the FY2010 Homeland Security Appropriations Bill on October 28, 2009, provides that the Act shall not apply to spring - assist or assisted - opening knives (i.e. knives with closure - biased springs that require physical force applied to the blade to assist in opening the knife). </P> <P> Each American state also has laws that govern the legality of carrying weapons, either concealed or openly, and these laws explicitly or implicitly cover various types of knives . Some states go beyond this, and criminalize mere possession of certain types of knives . Other states prohibit the possession and / or the concealed carrying of knives that feature blade styles or features sufficient to transform them into "dangerous weapons" or "deadly weapons", i.e. knives either optimized for lethality against humans or designed for and readily capable of causing death or serious bodily injury . These frequently include knives with specific blade styles with a historical connection to violence or assassination, including thrusting knives such as the dirk, poignard, and stiletto, the bowie knife, and double - edged knives with crossguards designed for knife fighting such as the dagger . Some states make the carrying or possession of any dangerous or deadly weapon with intent to unlawfully harm another a crime . </P>

When is a pocket knife considered a weapon