The laws in California are a little bit of a mixed bag and full of what some might call contradictions. California has many laws regarding most forms of gambling however it must be noted that these are aimed at individuals or groups of individuals who manage and operate illegal gambling venues across the state. Not once has a regular law abiding citizen been successfully convicted, in fact the cases are usually thrown out before they even begin. As long as you are keeping well clear of organized criminal activity then you have no worry. It is worth noting that California is currently in the middle of hearings regarding SB1485 which aims to legalize online poker. Also, California law always refers to "percentage games" when speaking of the illegality of poker, which being a little vague in regards to poker, allows certain loopholes to be exploited. Many residents of California currently enjoy playing online poker at rooms such as BetOnline Poker, and until these rules change they will continue to do so.
Playing at Home, Online or Offline
Playing at home either with a few friends round for a game, or enjoying a game online are basically governed by the same rules. The California Penal Code states that it is illegal to, "deal, operate, carry on, conduct, maintain, or expose for play in this state any controlled game". Within the definitions poker is actually classed as a controlled game. However enforcement of this law is rare and as long as you aren't profiting from the game in any other way than winnings then you will be fine. The same applies to online poker, and if you are not running an online poker site from your home, then you will have little to nothing to worry about. Many Californians play online at BetOnline Poker and Full Flush Poker right now. The online poker laws may and probably will change in the near future to totally legalize online poker and many states are in the consideration stage at the moment. Following Nevada with an intrastate model seems to be the way things are heading.
California Card Rooms and Casinos
It's in California's card rooms and casinos where you can see the loophole in the law being applied. It is by definition illegal to take a percentage rake, as that would be illegal, however that is not the only way to make money out of hosting a poker game. Most casinos will charge a fee depending on the amount of the pot, for example, up to $15, they will take nothing, $15 to $25 they could take $1.00 and keep going up on a sliding scale. You may think that this is just another form of taking a percentage and you would be correct, but in the eyes of the law there is a very big difference and that's how they do it.