You need to check your local penal codes.. In California (off the top of my head), a knife is not a switch blade / gravity knife if:

1) There is no switch on the HANDLE that opens the knife automatically, any stud or such on the BLADE does not count.
2) The knife has a natural tendency for closure (as the blade gets closer to the handle, it will automatically snap shut)
3) The knife has a natural tendency to remain closed

The last two I believe focus more on gravity and balisong type knives. Oh, I miss my balisong/butterflies...

Please note that outside of States restrictions, most big cities have additional restrictions (e.g. LA, CHI, NYC, etc).