There are a lot of boules on the ground. Your team (team A) has the point, and unplayed boules.
You ask the opponents (team B) if they have any more boules to play. They look around, don’t see any, and say “No, we’re out.” So your team plays a boule. Then one of the opponents says “Ooops! I made a mistake. Bob still has one boule left!”
What do you do?
One line of thinking is that team A’s last boule was a boule thrown contrary to the rules. Other commentators consider team A’s last boule to be a boule thrown out of turn. In both of these interpretations, team A is the party at fault. In our opinion however, in this situation team B is at fault, and team B’s forgotten boule should be declared dead.
In our opinion, one of the unwritten rules of petanque is—
Whenever asked, a team must willingly, honestly, and correctly report the number of unplayed boules it has.
Regardless of whether team B were trying to cheat, or made a mistake and genuinely forgot the boule, team B broke this unwritten rule. Allowing team B to go ahead and throw its forgotten boule would be, in effect, to take the boule advantage away from team A and give it to team B. But surely team A should not be punished for team B’s mistake. Here, we’re thinking of the second of our general principles for applying the rules.
A team that breaks the rules (deliberately or accidentally) should not benefit from its illegal action.
The bottom line is that team B should not be allowed to play their forgotten-and-then-remembered boule. The fogotten boule should be declared dead.
The situation would be different if team A hadn’t bothered to ask team B if they still had any unplayed boules, and had just proceeded to throw. Then team A, not team B, would have been at fault. In such a situation, it is the responsibility of the team about to throw to perform due diligence to verify that the opposing team is out of boules. If team A hadn’t done its due diligence, then team A’s boule truly would have been thrown contrary to the rules.
Asking the opposing team if they still have any unplayed boules should be sufficient, I think, to satisfy any reasonable requirements of due diligence. Some commentators are of the opinion that a team is required always to count, or keep a mental count of, the opposing team’s boules on the ground. That’s just silly. It would be difficult, time-consuming, and error-prone.
Here’s another way of thinking about the same situation. Implicit in the rule about a boule thrown contrary to the rules, there must be, by analogy, a mirror-image rule about a boule NOT thrown when the rules require that it MUST be thrown. At the time that team A asked team B if they had any unplayed boules, team B was required by the rules to reply “Yes” and to throw its last boule. But (for whatever reason) team B didn’t do it. Team B didn’t throw its last boule when the rules required that it be throw. So, like a boule thrown contrary to the rules, team B’s forgotten boule is dead.