Yup Russ. Good technique but requires reseating it n your grip. Also it's impossible to do with wet hands, so if your hands were bloody and you needed it for self defense one would be out of luck. Thats why went with the clip-it.

I really can't picture myself without a blade of some sort.
But wouldn't they be guilty of carry concealed weapons if they have the kitchen knives concealed, Chaos?
wonder what thet're stance s on people who carry knives as part of thier job? Say electritions, cable men, etc?

Ya, but the issue here is NYC laws, not whether or not a particular technique is practical. Any NYC cop can one-hand a 110 and at that point it's all over. From what I've heard, if they need to dry your knife and lube the pivot to make it flick open, no big deal. If they need to wipe the blood off your knife they'll probably just preserve it as evidence and look for the body.

By this definition of single handed opening by centrifugal force, is there a knife which is legal?

Very true Russ. Thanks for correcting me.

By the sounds of it, I think I'd stick with a traditional non-locking SAK or Leatherman Juice. For a locking blade, I'm wondering if something like the Leatherman Rebar or Super Tool 300 would be okay (the blades are on the inside, so you need to open the pliers to get at the blade first).

Butterfly knives are illegal to carry in the UK.
The 'carrying for your trade' reason is an out.
But I'll have a hard time explaining why this systems tester needs one.
qjs

I'm sitting here amazed how NYC has so many people living there, walking on egg shells constantly. Then again, in California, I had to adjust my way of thinking quite a bit after I became a gun owner. Now, navigating through the many gun laws is second nature.

I'm not an attorney and I don't live in NYC any more. I don't think the state law against concealed weapons applies to knives but you should consult an attorney.

NYPD will arrest people carrying knives, especially anything that can conceivably open with one hand. If you're in NYC, do not show anything clipped to a pocket or a waistband. Do not carry anything in a belt sheath. Like I said earlier, I know of at least one case where someone had to spend a lot of money to defend carrying a Leatherman multitool. My expectation is that anything more knife-like than that (such as any locking folder) will be even more expensive to defend in court.

It's not worth carrying a locking and/or one hand opening knife or multi-tool in NYC. I was going to suggest that a leatherman juice s2 was probably acceptable - but I just opened the (non-locking) blade one-handed!

If you need a multi-tool for your job (I don't) than I'd suggest you carry something like a rebar, with the blades inside, not one hand opening, and not carry it on your person, but in your carry case/bag. Unless they suspect you're a terrorist, the police are not going to check. I would never take any of these tools out in public, not even the SAK to clean your fingernails.

I spoke with an NY police LT. friend of mine several years ago - I had some sort of one hand opening pocket knife I was using - and without joking around, he made it clear that a hand hand opening and locking blade - not welcomed in the Big Apple.