A boule played out-of-turn is a boule that was played when a team mistakenly believed that they did not have the point, and that it was their turn to play.
For a long time, there has been serious debate about what should be done when this happens. Some have argued that a boule played out-of-turn was played “contrary to the the rules” and that Article 24 therefore gave the opposing team the option to declare it to be dead. Others have argued that a boule played out-of-turn was NOT an infringement of the rules but simply a mistake; boules played out-of-turn should stay where they are and play should continue.
This debate has now been settled by a ruling by the FIPJP. It is now official— a boule played out-of-turn is simply a mistake; it should be left in place and play should continue.
I don’t know if this ruling can be found on the FIPJP web site, but it was posted on the FFPJP (French) Guide de l’Arbitrage on March 6, 2023. You can read our English translation HERE.
The … ball played by mistake will be valid until the end of the mène.
This ruling made its way to the “Ask the Umpire” Facebook forum on May 4, 2023. In two separate posts (HERE and HERE) Tony Kidd, Trudy Bishop, Allen Cassady, and Andries Wijand all asked roughly the same question:
If Team B gains the point, but does not measure and (thinking that they have not gained the point) plays a second boule, what is the penalty?
Mike Pegg’s answers (which I have combined and compressed for the sake of readability) were—
The penalty is that Team B has wasted one of its boules. No boules are removed, and play continues. Team B of course should have checked [to verify that they were not holding], but so should team A to be sure they are still holding. If neither team checks to see who is holding, they are both in the wrong. Team B’s second boule remains valid, and they are at a disadvantage having played a boule they didn’t need to play.
It is nice to have this old thorn in the side finally pulled.
The Rules of Petanque 
Note that the boule remaining in place is not necessarily a penalty. Such a boule could even have been played out-of-turn on purpose in order to ‘shield’ the jack and make it more difficult for the opponents to reach it.
The downside of playing a boule out-of-turn is that it reduces or eliminates any boule advantage that your team has. This is such a serious disadvantage that I doubt that any team would deliberately play a boule out-of-turn, for any reason. See https://petanquerules.wordpress.com/2021/12/21/the-boule-advantage/