Seit 1358/59 sollten alle Mitglieder des Hauses Habsburg durch das Privilegium Maius, eine Urkundenfälschung von Leopolds ältestem Bruder, dem Herzog Rudolf IV. (1339-1365), den Titel "Erzherzog" führen: "Unwilling to accept the omission of his family from the college of prince electors, when Emperor Charles IV established it in his Golden Bull, Rudolf tried to use forged privileges, claims to the titles of "Duke of the Palatinate," "Duke of Swabia," and "Grand Master of the Hunt," as well as the claim to wear an arched crown and other insignia of sovereignty, to obtain for himself and for his House a special position with privileges exceeding even those of the prince electors. Though he wished to see the Austrian ruler protected from any interference by imperial power, his own right to dispose freely of crown land and also his authority over the landed nobility were to be increased in every way, and the ruler and his country were to take special rank as 'the heart and shield of the Empire'. ... Even though the word 'Arch-house' did not appear for some time, it nevertheless stemmed from the title of archidux, archduke, first claimed by Rudolf IV, although established in the family only later. This archducal title was not a pure figment of the imagination, but came from the 'extremely ancient' duchy of Carinthia. There the investiture of the duke took place, according to time-honored custom, on the Zollfeld (toll field), which was regarded as proof that the ducal rank was rooted in native soil, and was independent of all higher power. Accordingly, during the period when the family was divided, only the branch that held Carinthia reassumed the archducal title (the first was Ernest the Iron Duke, father of Frederick III)." (in: Adam Wandruszka: The House of Habsburg - Six Hundred Years of a European Dynasty, London 1964, pp. 65-67).
Der Rang eines Erzherzogs, erklärt vom Erzherzog Albrecht von Österreich-Teschen (1817-1895): " ... a title more ancient and therefore more highly esteemed than that of any Grand Duke or Prince Elector. An Archduke does not de iure yield precedence to these, only to a crowned head (Majesty), because the Austrian Archdukes, each one of whom is invested with the Archduchy, have never lost the privileges of rank due to them as ruling peers." (in: Adam Wandruszka: The House of Habsburg - Six Hundred Years of a European Dynasty, London 1964, p. 169).