If the ball lands in the 0 slot, the usual rule is that the house takes everything except bets on 0. However, some casinos use a rule called en prison that gives the player a last chance to save his or her chips.
En prison is allowed only if the original bet was on one of the spaces that gives 50/50 odds of winning, such as the even-odd or red-black spaces. The player may choose to leave the chips there for another spin of the wheel, usually with a marker to indicate the chips are en prison. If the result of the next spin is a win, the player gets his or her en prison stake back. If not, the chips are lost.
The en prison rule is widely used in European casinos, but can be hard to find in America. A few big casinos in Las Vegas allow it. Atlantic City casinos use a variation of en prison called la partage or surrender, under which only half of an even-money bet is lost when a 0 comes up.
Allowing en prison reduces the house edge by giving players a chance to cut their losses on a 0 spin. For a serious roulette player, it’s definitely worth it to find a casino that allows en prison. Every numerical advantage, no matter how small, helps!
