As plaintiffs seek relief holding the law void for vagueness as to an entire category of folding knives, the challenge is construed as a facial challenge; a past enforcement against one of the plaintiffs provided sufficient notice of the proscribed activity, establishing that it is possible to enforce the law constitutionally -- therefore not facially unconstitutional. While it is possible to enforce the law in a discriminatory manner, and there might be evidence of this discrimination in past enforcement, the law itself does not unduly invite such discrimination.
http://www.ca2.uscourts.gov/decisions/isysquery/37d309e7-2938-46a7-887d-c286c9866ef7/2/doc/17-474_opn.pdf#xml=http://www.ca2.uscourts.gov/decisions/isysquery/37d309e7-2938-46a7-887d-c286c9866ef7/2/hilite/
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.