Vested or Acquired Right (Droit acquis)

Law which having entered in a patrimony under a law or under old rules, cannot be challenged by the application of a new law or new rules. Acquired right in respect of a site, a construction, a use or a sign permits to maintain and enjoy a factual situation even if this situation is no longer consistent with the new planning regulation. Recognition of acquired right is based on a principle which states that, in general, laws and regulations are not retroactive, that is to say they cannot undermine existing situations before their entry into force, unless specified by law.