In the medieval Spanish monarchies, whether Castilian, Leonese, Navarran or Aragonese, all sons and daughters of the monarchs, including the firstborns, were infantes.

By birth, the firstborns of the kings had the title of infante like their brothers and sisters, but when they were proclaimed as heirs before the Cortes, they then became Princes of Asturias.

[5] The same happened in Navarre, when Charles III created for his grandson, the Infante Carlos, son of his daughter Blanca and the future John II of Aragon, the title of Prince of Viana, with the idea that this title should be passed to the heirs of the Crown of Navarre.

Their consorts, as long as they remain as such or as widowers, have the style and honours that the King graciously grants them according to the provisions of article 62, section f) of the Constitution.2.

Also, the King can grant the dignity of Infante and the style of Highness to the persons that he judges worthy of this honours by the existence of exceptional circumstances.3.