http://www.cleverscampcamp.com/knife-case/

is it illegal to have a butterfly knife in New York?
Alright, I did a lot of research and i saw that the law says you can’t have a gravity knife. and that a court case said the butterfly knife is not a gravity knife.
it also says that on the wiki.
Ive bought 1 butterfly knife a few months ago online, and it shipped it and everything no problems at all and i received it.
My question is, is this illegal?
yes
Case Knives