The absence of boundary markers made invalid the determination of boundaries carried out by two neighbours, a French court has ruled.

In deciding the case the French Supreme Court (Cour de Cassation) overturned a decision of the lower court of appeal who had decided that, because the neighbours had some years previously determined the boundary between them, the court could not now interfere in the matter.

The case turned on the legal right of a property owner with a contiguous property to another to seek a judicial ruling on the boundary between them (Article 646 of the Civil Code).

The right exists where two neighbours cannot agree amicably on their boundary.

In this case, it seems that several years previously the neighbours had been able to do just that, and a written agreement, together with a plan with the boundary marked on it, were produced in the court.

It was on the basis of this agreement struck in 2003, when there had been a sale of some land between them, that the court of appeal declined to hear the case.

However, even though it seems there were features on the ground that the two parties used to identify the boundary, the Cour de Cassation decided that this was insufficient, and that boundary markers (bornes) should have been implanted in the ground, which should have then been marked on the plan.

The effect of the ruling was to invalidate the agreement that had been struck amicably between the parties, and to require that the process be undertaken again, if necessary by determination of the court.

One of the issues not considered by the court was the fact that the parties had not registered their agreement with the land registry.

In this case it was less important to have done so, as they each remained the owners of the land in question.

However, without formal registration of a boundary determination with le service chargé de la publicité foncière (formerly called la conservation des hypothèques) it does not bind their successors.