The Amarr Heirs are the heads of the five royal families, the highest caste of the Holders apart from the Emperor family itself. Even if the emperor is the head of state his power outside his immediate vicinity is limited. The entrenched bureaucracy and the semi-feudal governing system means that all over the empire there are local lords that enjoy almost complete autonomy most of time. The Heirs are the most powerful of these lords. Each heir family has vast domains spanning dozens of solar systems. The power of the heirs can best be seen in the way each of them shapes their domain to fit his own wishes. The result is that the Amarr Empire is a patchwork of rules and regulations, customs and traditions.
The power of the heir families originates in the changes made during the Moral Reform some 1500 years ago, when the influence of the Apostles was curbed. The Privy Council, the unofficial government of the empire, also dates from this time and all the heirs sit on it.