Pennsylvania - Pa. C.S.A. 18.908. Prohibited offensive weapons.
(a) Offense defined.--A person commits a misdemeanor of the first degree if, except as authorized by law, he makes, repairs, sells, or otherwise deals in, uses, or possesses any offensive weapon.
(b) Exception.--it is a defense under this section for the defendant to prove by a preponderance of evidence that he possessed of dealt with the weapon solely as a curio or in a dramatic performance, or that he possessed it briefly in consequence of having found it or taken it from an aggressor, or under circumstances similarly negativing any intent or likelihood that the would be used unlawfully.
(c) Definition.--As used in this section "offensive weapon" means... any... dagger, knife, razor or cutting instrument, the blade of which is exposed in an automatic way by switch, push-button, spring mechanism, or otherwise... - also see 24 P.S. 13-1317.2. re: students bringing weapons on to school property.]
Pennsylvania case law: Where opening knife required lock to be released, and once lock was released blade could be exposed by flip of wrist, knife did not have blade which could be "exposed in an automatic way"... by "otherwise" legislature referred to knives that were opened by some sort of mechanism which is not a "switch," "push-button," or "spring" mechanism but still a mechanism... (1979)
If you care to learn about the laws in all the other states, please go here Knife Laws
This information is provided as an exercise of
the 1st Amendment. I am not a legal authority
nor do I practice law. I do carry a knife....or
two....or three on occasion.