Albert's lack of legitimate children until the 2010s prompted Prince Rainier III to change the constitution so as to ensure there would be a successor to the throne, which strengthened the places of Caroline and her descendants in the line of succession. On 2 April 2002, Monaco passed Princely Law 1.249, which provides that if the Sovereign Prince assumes the throne and then dies without a legitimate direct heir, the throne will pass to his dynastic siblings and their descendants according to the rule of male-preference cognatic primogeniture. The law was then ratified by France, as required by a 1918 Franco-Monégasque Treaty, on 4 October 2005. Before this change, the crown of Monaco could pass only to a descendant of the last reigning prince, excluding such collateral relations as siblings, nephews, and nieces.