For a friend I wrote this quick summary of the crazy CA knife laws. I'm not a lawyer. Also, I'm not including city or county laws, which add reams more crazy to the mix.

To summarize:
Banned outright are special knives, like spetznaz ballistic knives, belt buckle knives, cane swords, shuriken, butterfly knives over two inches, knives that look like pens, and knives with grips that serve as brass knuckles, like the Stinger or the Shocker whatever the kids call it these days.
Folding knives are not concealed (and thus legal) when folded, anywhere on your body unless they're like gravity knives or switchblades. There are length limits if you're in a school.
Fixed blades, daggers, or similar pokey objects (edges don't count, I think) MUST BE IN A SHEATH ON YOUR BELT (openly suspended from the waist) otherwise they're concealed, which means jail time. Technically, the "openly suspended from the waist" bit isn't in there anymore, but cops aren't going to know that, and it should stand up in court just fine. Wrist sheaths, underarm sheaths, boot knives, neck knives are right out, unless you feel like making a case that it's not concealed where it is.
The Carson Flipper / The Wave is not banned yet.
Anything of four inches or over can't be in a meeting that's required to be open to the public, including court.
Plastic knives can't be sold or made or caused to be made.
Platic concealed knives are just trouble.
Don't take knives into the airport.
Also, it has nothing to do with laws, but get a reciept if the police confiscate ANYTHING. It's just a good idea.

some laws
other laws
I'm still not a lawyer.