Any Idea why Butterfly knives and Switchblades are illegal in some states and countries like Canada?
Concealable? you can hide all kinds knives anywhere any way you like and they are just as concealable as any other. You can freaking hide a sawed off shot gun for gods sake.
Fast to take the blade out? Butterfly knives takes skill to open it properly. My friend who bought a Butterfly knife in Chinatown (illegally) kept getting cut because he couldn't even open it right. There are also many legal foldable knives out there you can tweak so it acts just like a switchblade.
There is almost NO justification to make these things illegal
you might as well have some sort of mandatory background checks for kitchen knives too.