[BBB333]

There are many assisted opening knives legal in the United States.

Here is a great example: Kershaw Scallion Folding Knife with SpeedSafe

http://www.amazon.com/Kershaw-1620NB-Scallion-Folding-SpeedSafe/dp/B00AU6NLMS?ie=UTF8&keywords=kershaw%20scallion&qid=1462196749&ref_=sr_1_1&sr=8-1

It is not a switchblade - a switchblade’s blade loads a spring and is kept in place with a latch.

These knives have a torsion bar which keeps the blade in the closed position and also helps it open and lock - no latching mechanism whatsoever.

Excellent knives and extremely easy to open (automatically) and close with one hand.

[TangoLimaSierra]

Amazon

This is a spring assisted knife I own.

Amazon

[Billthedrill]

Kershaw Scallion Folding Knife with SpeedSafe

Oh, yeah. My EDC knife is a Kershaw Leek. It isn't a prybar, it isn't a screwdriver, it isn't a ninja weapon, it's a knife, and I feel naked without it even if I'm wearing a business suit.