It's illegal to carry mace here too...you need a 'concealed weapon' permit. Knives, on the other hand, are perfect legal in my state so long as its not a switch blade. Mine isn't. Of course, I loosened the flip screw to make it really easy to open the knife...

It's pretty statistically proven that even if you *aren't* carrying a knife, SAYING that you are actually gives an attacker pause because that's an altercation that they weren't expecting. Actually having one is just a comfort measure. Next time I go to England I won't have it though, 'cause I won't be carrying on the plane...