Article 591 of the French Code of civil procedure

The decision that upholds the third party opposition only retracts or amends the contested judgment in respect of the points that are prejudicial to the third party opponent. The original judgment retains its effect between the parties, even in respect of the aspects that have been set aside.

The original judgment retains its effect between the parties, even in respect of the aspects that have been set aside.
However, res judicata on a third party opposition is res judicata in respect of all the parties called to the proceedings pursuant to article 584.

Original in French 🇫🇷

Article 591

La décision qui fait droit à la tierce opposition ne rétracte ou ne réforme le jugement attaqué que sur les chefs préjudiciables au tiers opposant. Le jugement primitif conserve ses effets entre les parties, même sur les chefs annulés.

Toutefois la chose jugée sur tierce opposition l’est à l’égard de toutes les parties appelées à l’instance en application de l’article 584.