Since 1991,
Belgium practises
absolute primogeniture among the descendants of
King Albert II (then Prince of Liège). Descendants of earlier monarchs and princes are only eligible to succeed if male and descended from
King Leopold I in male-line (i.e. according to
agnatic primogeniture), meaning that descendants of all Belgian princesses not descended from Albert II are barred from the throne. There are no living princes of Belgium who are not descended from Albert II, so agnatic primogeniture
de facto no longer applies, and the right to succeed is effectively limited to Albert II's descendants. Should there be no eligible descendant of
King Leopold I, the reigning monarch may name his or her
heir presumptive with the approval of the Parliament, but if she or he doesn't name the heir presumptive, the throne would eventually become vacant. In the case of a vacancy, Parliament would appoint a Regent (see
below), then elections would happen within two months, and the new sitting of Parliament would jointly appoint the next monarch. When King Albert II's daughter
Astrid married
Archduke Lorenz of Austria-Este in 1984, agnatic primogeniture being in effect, she had no succession rights and therefore did not seek the consent to her marriage. Following the introduction of absolute primogeniture among her father's descendants in 1991, it was deemed that she had obtained the necessary consent and thus assumed her place in the line along with her children. When
Prince Amedeo married in 2014, it was reported that he did not ask his uncle King Philippe's permission, and had therefore lost his right to the Belgian throne. However, on November 12, 2015, a Royal Decree was published which showed that consent had been given after the marriage retroactively. In October 2020 the
Belgian Court of Appeals granted the title of Princess to
Delphine Boël, the illegitimate daughter of King Albert II, but because of her being born out of wedlock, she did not enter the line of succession. Since she was born in 1968 after her three legitimate half-siblings she would not displace any of her kin regardless and would only come after her half-nephew
Prince Aymeric. No foreign head of state may become Belgian monarch, unless both Houses of Parliament separately agree to it, two-thirds of the Members being present in each House, and a two-thirds majority being required in each House. == Accession ==