Here is a Frequently Asked Question about moving a boule during measuring.
Article 28 of the 2016 version of the FIPJP rules says:
The point is lost by a team if one of its players, while making a measurement, displaces the jack or one of the contested boules.
Here is a typical situation that raises questions about this rule:
Boules A1 and B1 are “contested boules”, that is, they appear to be about the same distance from the jack and it is not clear which one of them holds the point. While measuring, Albert (from team A) accidentally bumps boule B1 a few millimeters farther away from the jack. So (per Article 28, because Team A moved a boule while measuring) Team A loses the point. Boule A1 loses the point, boule B1 has the point, and Team A plays the next boule.
During the agreement of points, Team A starts to use the normal point-counting procedure. The relative positions of A1 and B1 have not changed. A1 is closer to the jack than B1, so Team A naturally says that A1 beats B1. Team B disagrees, arguing that A1 earlier lost the point to B1. What is the correct ruling?
In a reply to this question on Ask the Umpire, Mike Pegg has ruled that as long as none of the involved balls (jack, A1, B1) has been moved, when points are counted A1 cannot be counted as beating B1. In other places he has ruled that A1 does not count in a measure for points as long as neither the jack nor A1 has been moved during play. The bottom line is that Team B is correct— when points are counted, A1 must still be considered farther away from the jack than B1.
Accidentally moving a ball while measuring is an illegal event. An “illegal event” is an event that is not possible within the rules of the game, but that is physically possible and actually occurs in real life. (In chess, for instance, accidentally upsetting the board is not a legal move, but sometimes it happens.) The ideal response to an illegal event is to undo it: to put everything back where it was before the illegal event occurred. In petanque, this would mean that the two teams would agree on how to put the illegally-moved things back. (This is the philosophy of Petanque Libre.)
When nothing is marked, an FIPJP umpire must rule that everything should be left where it is. Interestingly, Mike Pegg has suggested that it is possible for the two teams to agree to undo an illegal event even in a game supervised by FIPJP umpires. If an unmarked boule is moved accidentally, he says, agree with your opponent to replace the boule. “Do not call the umpire because if you do he or she will say the boule must remain where it is.”
Read other posts in the Putting Things Back category