En Prison is a settlement rule that appears mainly in French roulette. It changes the outcome of even‑money bets when the ball lands on zero. Instead of losing the stake outright, the wager is placed in a “prison” for the next spin. If the same bet wins on the following spin, the original stake is returned; if it loses, the player loses the stake. The rule is intended to soften the impact of the zero, which otherwise gives the house a slight advantage.
On a typical online platform, the software detects a zero result and flags all eligible bets. The stake is stored in a temporary state and the bet is marked as pending. The next spin is processed normally, but the system checks the pending status. A win on the same even‑money wager triggers a refund of the original amount, while a loss simply clears the pending flag. Players can see the pending amount in their balance or a dedicated status indicator.
Because the En Prison rule only applies to a subset of bets, the overall return to player (RTP) for the game is slightly higher than a standard French table without the rule. The rule effectively reduces the house edge by about 0.02% on even‑money bets. However, the benefit is contingent on accurate random number generation and correct implementation of the rule by the casino’s software engine. Any deviation can distort the expected payout.
One area where weak points can surface is the transparency of the rule’s implementation. For additional context, casino utan svensk licens can be considered alongside this overview. If a casino does not clearly explain how pending bets are handled or if the software misclassifies a bet, players may unknowingly lose more than expected. For example, a glitch that forces a pending bet to be treated as a loss on the next spin removes the intended advantage, as discussed in .
Regulatory bodies require that online casinos undergo independent audits to verify that the En Prison rule operates as advertised. Auditors examine the source code, test scenarios, and audit logs to ensure that pending bets are correctly resolved. Additionally, responsible gambling tools such as self‑exclusion, deposit limits, and session timers help players manage risk before the rule even comes into play.
When reviewing a casino’s roulette offering, look for explicit mention of the En Prison rule in the terms of service or game rules section. Reputable software providers publish white papers or documentation detailing how the rule is coded. If a site offers a free demo mode, observe how a zero outcome is handled to confirm the expected behavior.
The En Prison rule can make a noticeable difference for players who frequently place even‑money bets, but it does not eliminate the inherent uncertainty of roulette. A well‑regulated environment, transparent rule description, and robust testing are key to ensuring that the intended advantage is preserved. Players should remain aware of the rule’s mechanics and continue to set personal limits, keeping the experience both enjoyable and responsible.