I was stopped a few years ago for having a Spyderco Delica knife poking out of my back pocket. The way it was explained to me is what are illegal are so-called gravity blades, blades you can open one-handed that lock open, and have to be unlocked (say, with a liner lock) to be closed. So, the old Case knife currently nestled in my front pocket is fine, but that Buck Redpoint you saw in the catalog ain't.
That being said, I do know of fellas who have been stopped with larger knives who claimed they needed them for work (one guy was a butcher) and the cops let them go.
In the immortal words of Mr. Spock, "Live long and suck it!"
IBA # 55612