I wont ask for specifics, but blades under 4 inches are generally OK in NYC. There was a discussion last year about a guy charged with a similar crime who had a under 4-inch knife and eventually got the charges dropped. You might do a search and send him a private message to get the name of his lawyer.
Edit: Found the threads
http://thefiringline.com/forums/show...ice+harassment
and
http://thefiringline.com/forums/show...knife+new+york
Bubsy was the members name.