Note that almost all knives people consider to be switchblades are actually "assisted open" knives instead. The law very specifically requires a switchblade be

Note that almost all knives people consider to be switchblades are actually "assisted open" knives instead. The law very specifically requires a switchblade be opened by pressing a button on the handle. (They're generally implemented by a spring pushing on the blade and a catch released by the button). An assisted open knife has you start opening the knife by applying pressure to a stud on the /blade/ which causes a spring which had been holding it closed to continue opening it instead. These do not meet the definition of "switchblade" and are not illegal in most jurisdictions.