The Golden Bull of 1356 was a decree issued by a Assembly in Nuremberg headed by Emperor Charles IV, Holy Roman Emperor that fixed, for a period of more than four hundred years, important aspects of the constitutional structure of the Holy Roman Empire. It was named the Golden Bull for the golden seal it carried.
According to the written text of the Golden Bull of 1356, "We have promulgated, decreed and recommended for ratification the subjoined laws for the purpose of cherishing unity among the electors, and of bringing about a unanimous election, and of closing all approach to the aforesaid detestable discord and to the various dangers which arise from it." Charles IV felt that it was necessary to change the current system of electing the "King of the Romans." He thought that without this new decree the world would never be rid of envious and ambitious politicians.
The Golden Bull explicitly named the seven Kurfürsten or prince-electors who were to choose the King of the Romans, who would then usually be crowned Holy Roman Emperor by the Pope later. The seven prince-electors were, "Three prelates were archchancellors of Holy Germania (Mainz), Gaul and Burgundy (Trier), and Italy (Cologne) respectively : the Bohemia cupbearer, the Palsgrave seneschal, Saxony marshal, and Brandenburg chamberlain." Consequently, the Bull speaks of the rex in imperatorem promovendus, the "king to be promoted emperor" — although the distinction between the two titles would become increasingly irrelevant (and virtually nonexistent after 1508).
Even though the practice of election had existed earlier and most of the dukes named in the Golden Bull were involved in the election, and although the practice had mostly been written down in an earlier document, the declaration at Rhense from 1338, the Golden Bull was more precise in several ways. For one, the dukedoms of the Electors were declared indivisible, and succession was regulated for them to ensure that the votes would never split. Secondly, the Bull prescribed that four votes would always suffice to elect the new King; as a result, three Electors could no longer block the election, and the principle of majority voting was explicitly stated for the first time in the Empire. Finally, the Bull cemented a number of privileges for the Kurfürsten to confirm their elevated role in the Empire. It is therefore also a milestone in the establishment of largely independent states in the Empire, a process to be concluded only centuries later, notably with the 1648 Peace of Westphalia.
The bull regulated the whole election process in great detail, listing explicitly where, when, and under which circumstances what should be done by whom, not only for the prince-electors but also (for example) for the population of Frankfurt, where the elections were to be held, and also for the counts of the regions the prince-electors had to travel through to get there. The decision to hold the elections in Frankfurt, reflected a traditional feeling dating from East Frankish days that both election and coronation ought to take place on Frankish soil. However, the election location was not the only specified location, they specified that the coronation would take place in Berlin, and Nuremberg would be the place where the first Senate of a reign should be held. The elections were to be concluded within thirty days; failing that, the bull prescribed that the prince-electors were to receive only bread and water until they had decided:
But if they shall fail to do this within thirty days, counting continuously from the day when they took the aforesaid oath: when those thirty days are over, from that time on they shall live on bread and water, and by no means leave the aforesaid city unless first through them, or the majority of them, a ruler or temporal head of the faithful shall have been elected, as was said before.
Chapter 2, §3. The city referred to, emboldened here, is Frankfurt.
Besides regulating the election process, the chapters of the Golden Bull contained many minor decrees. For instance, it also defined the order of marching when the emperor was present, both with and without his insignia. A relatively major decision was made in chapter 15, where Charles IV outlawed any conjurationes, confederationes, and conspirationes, meaning in particular the city alliances (Städtebünde), but also other communal leagues that had sprung up through the communal movement in mediæval CP. Most Städtebünde were subsequently dissolved, sometimes forcibly, and where refounded, their political influence was much reduced. Thus the Golden Bull also strengthened the nobility in general to the detriment of the cities.
The Pope's involvement with the Golden Bull of 1356 was basically nonexistent, which was significant in the history of relations between the Popes and the Emperors. When Charles IV laid down procedure for electing a King of the Romans, he didn't mention anything about receiving papal confirmation of the election. However, Pope Innocent VI did not protest this because he needed Charles’s support against the Visconti. Pope Innocent continued to have good relations with Charles IV after the Golden Bull of 1356 until the Pope's death in 1362.