Switchblade

A switchblade is a pocketknife whose blade, held in the handle, is driven open automatically by an internal spring when a button, lever or switch on the handle or bolster is pressed, and almost all designs also lock the blade open until it is deliberately released for closing. The knife's automatic opening action, rather than any single inventor or date, defines the type, and it spans folding knives made in many countries. In the United States, media coverage in the 1950s linked switchblades to youth crime, prompting Representative James J. Delaney to introduce the first congressional bill restricting their manufacture and sale in 1954, a wave of restriction that spread to other countries and curtailed the knife's popularity.