580th Anniversary the Opening of the Council of Basle, July 25, 1431 (17th Ecumenical Council)
[If the apostolic see becomes vacant while the council is in progress, the election may not be held outside the council]'
The holy general synod of Basel, legitimately assembled in the holy Spirit, representing the universal church, bears in mind that it pertains to the duty of providence to foresee the future with clear-sighted consideration and to take wholesome steps against what could bring harm to the common good. The synod is intent upon the extirpation of heresies, peace among the people of Christ and the reformation of morals, with the grace of the holy Spirit, as is really necessary in view of the present situation. It has summoned the venerable fathers in Christ, the cardinals of the holy Roman church, to this sacred council, convinced that their presence at it is fruitful in many ways in view of their authority, wisdom and knowledge of affairs. If, then, as obedient sons they are coming to the council when the apostolic see falls vacant elsewhere, such a situation would redound to the benefit of the church but the obedient cardinals would be serving the council to their own disadvantage, whereas everyone knows that obedience should bring with it not disadvantage but an increase of benefit and honour. Lest disobedience may seem to be to the advantage of some who fail to come, this holy synod, with purposeful anticipation and for the above and other reasons which can and should motivate a prudent mind establishes, decrees and defines that, in the event of a vacancy of the apostolic see while this sacred council is in progress, the election of the supreme pontiff shall be held in the place of this sacred council, and it forbids it to be held elsewhere. The synod also decrees that any attempt against this by any authority whatsoever, be it even papal, notwithstanding any constitutions issued or to be issued or anything else acting to the contrary, even if there should be special mention in so many words or a confirmation on oath, which the synod rejects with full knowledge, is null and void and of no force or importance by law; and that those who attempt such things shall be disqualified in both active and passive voice with respect to the election of a Roman pontiff and for every other dignity, and deprived perpetually of all dignities which they hold, and shall automatically incur the mark of infamy as well as sentence of excommunication. If any such pretended election should be attempted, then both the one allegedly elected and his supporters as well as those who treat him as elected incur in the same way the above-mentioned penalties. The said synod reserves to itself, except at the moment of death, absolution of everyone who in any way shall incur the said sentences or any one of them. It declares that the present decree shall bind and come into force after forty days following its publication.