Roulette is not legal in California. But the altered version of roulette available in tribal casinos  aka California roulette  is legal. During the late 1990s, California and many of the Native American tribes there began signing tribal-state gambling compacts.

Indian Casinos\n\n The only Vegas-style casinos allowed in California are located on Tribal Land. This type of gambling uses banking/percentage collection. In other words, it takes money from the losers of the game and uses that money to pay the winners while taking a cut  for the house (or casino).