In nomine Domini

The bull was issued on 13 April 1059[note 1] and caused major reforms in the system of papal election, most notably establishing the cardinal-bishops as the sole electors of the pope, with the consent of minor clergy.

[3] Such a nomination under the canon law was not a valid election[4] and the legal electors would have to ratify the choice, though undoubtedly they would naturally be swayed by circumstances to give effect to the imperial preference.

[5] Stephen IX's election had obtained the consent of the empress-regent, Agnes of Poitou, despite the omission of the traditional preliminaries and the waiting of the cardinals for the imperial nomination.

[note 3] Keen to avoid future controversy in papal elections and to curb the outside influence exerted by non-ecclesiastical parties, in April 1059 he summoned a synod in Rome.

The procedure and rules can be summarised as follows: The bull was followed by an alliance between the papacy and Robert Guiscard, who was made Duke of Apulia and Calabria and Sicily by the Holy See in exchange for annual tribute and him guaranteeing the security of the See of Saint Peter.