Papal bull
A Papal bull is a particular type of letters patent
Letters patent
Letters patent are a type of legal instrument in the form of a published written order issued by a monarch or president, generally granting an office, right, monopoly, title, or status to a person or corporation...

 or charter issued by a Pope
The Pope is the Bishop of Rome, a position that makes him the leader of the worldwide Catholic Church . In the Catholic Church, the Pope is regarded as the successor of Saint Peter, the Apostle...

 of the Catholic Church. It is named after the bulla
Bulla (seal)
Bulla , is a type of seal impression. It comes in two forms: metal and clay.- Clay bullae :The original bulla was a lump of clay molded around a cord and stamped with a seal...

 that was appended to the end in order to authenticate it.

Papal bulls were originally issued by the pope for many kinds of communication of a public nature, but after the fifteenth century, only for the most formal or solemn of occasions. Modern scholars have retroactively used the term "Bull" to describe any elaborate papal document issued in the form of a decree
A decree is a rule of law issued by a head of state , according to certain procedures . It has the force of law...

 or privilege
A privilege is a special entitlement to immunity granted by the state or another authority to a restricted group, either by birth or on a conditional basis. It can be revoked in certain circumstances. In modern democratic states, a privilege is conditional and granted only after birth...

 (solemn or simple), and to some less elaborate ones issued in the form of a letter.

1054    Three Roman legates break relations between Western and Eastern Christian Churches through the act of placing an invalidly-issued Papal Bull of Excommunication on the altar of Hagia Sophia during Saturday afternoon divine liturgy. Historians frequently describe the event as the start of the East-West Schism.

1252    Pope Innocent IV issues the papal bull ''ad exstirpanda'', which authorizes, but also limits, the torture of heretics in the Medieval Inquisition.

1256    The Grand Union of the Augustinian order formed when Pope Alexander IV issues a papal bull ''Licet ecclesiae catholicae''.

1256    The Augustinian monastic order is constituted at the Lecceto Monastery when Pope Alexander IV issues a papal bull ''Licet ecclesiae catholicae''.

1302    Pope Boniface VIII issues the Papal bull ''Unam sanctam'' (One Faith).

1343    Pope Clement VI issues the Bull ''Unigenitus''.

1348    Papal bull of Pope Clement VI protecting the Jews accused to have caused the Black Death.

1377    Pope Gregory XI issues five papal bulls to denounce the doctrines of English theologian John Wycliffe.

1484    Pope Innocent VIII issues the ''Summis desiderantes'', a papal bull that deputizes Heinrich Kramer and James Sprenger as inquisitors to root out alleged witchcraft in Germany and leads to one of the most oppressive witch hunts in European history.

1503    James IV of Scotland and Margaret Tudor are married according to a Papal Bull by Pope Alexander VI. A Treaty of Everlasting Peace between Scotland and England signed on that occasion results in a peace that lasts ten years.