In accordance with the terms of Article 71 of the Constitution, the crown of the Grand Duchy is hereditary in the Nassau family in accordance with the pact of 30 June 1783, Article 71 of the Treaty of Vienna of 9 June 1815, and Article 1 of the Treaty of London of May 11, 1867.
The 1815 Treaty of Vienna gave the Grand Duchy of Luxembourg the order of succession established between the two branches of the House of Nassau by the family pact of 1783.
In June 2011, gender equality in the line of succession was introduced by modification of the family pact of 1783, the internal agreement of the House of Luxembourg-Nassau. This new order of succession will apply for the first time to the descendants of Grand Duke Henri.
The Family Pact of 1783
Before 2011, the family pact stipulated as follows: The crown is handed down in a direct line by order of male primogeniture, to the exclusion of female descendants. If there is no male issue in a direct and collateral line in one of the branches of the House of Nassau, the crown is automatically handed down to the male descendant of the other branch. If there is no male descendant in either branch, the crown is handed down by order of primogeniture to the female descendant of the reigning dynasty.
It is through these principles that the personal union of the Grand Duchy with the Netherlands ended in 1890. After the death of William III of the Netherlands, the Grand Duchy then passed into the hands of Duke Adolf of Nassau, head of the elder branch, while the only daughter of William III, Wilhelmina, succeeded her father to the throne of the Netherlands, which is governed by a different order of succession to that of the Grand Duchy.
The Family Statute of 1907
Grand Duke William IV, father of six princesses but without a male heir, promulgated a new family statute on 17 April 1907, proclaiming his eldest daughter, princess Marie-Adélaïde, as his heir to the throne. In the event that she would not leave a descendant, the new statute stated that the younger princesses were to follow on the throne in the order of primogeniture. The statute of 1907 was subject to ratification by the Chamber of Deputies and became law on 10 July 1907.