Well for starters you can carry one as long as the blade is under two inches (hence all the "California legal" models on the market).
California Penal Code section 653k provides that "Every person who possesses in the passenger's or driver's area of any motor vehicle in any public place or place open to the public, carries upon his or her person, and every person who sells, offers for sale, exposes for sale, loans, transfers, or gives to any other person a switchblade knife having a blade two or more inches in length is guilty of a misdemeanor."
It doesn't say anything about possession in your home, but technically speaking you probably can't transport one to your home without breaking some law. The reality is as long as you're not up to no good, it's probably not a big deal to have some in your collection. Of course your mileage may vary.
Best regards,
Argyll