ABSTRACT
The Grand Duchy was an empire because in the second half of the fourteenth century it became the largest state in Europe. Until its conversion to Catholicism in 1387, it did not recognise any international or interpolity jurisdiction above its own, i.e., it was completely sovereign. Personal or dynastic unions with the Kingdom of Poland did not undo that sovereignty either, as the Grand Duchy's ruling elite used union ties to serve the aims of its policy more often than the ruling class in Poland could. The second half of the fifteenth century in the Grand Duchy was marked by a lack of political will because of the differences between the dynastic interests of the Jagiellonians and the state interests of the Grand Duchy. Most historians of the Grand Duchy confuse indirect rule with federalism, calling the Grand Duchy a federation. Their mistake disregards the idea of federation established in constitutional law theory.
