The Council of Constance (1414-1418) convened in order to resolve three issues. First, it was to unite the church in the wake of a schism between three rival popes–Gregory XII, Benedict XIII, and John XXIII. The Council of Pisa (1409) had attempted to elect a new pope, Alexander V, who died only a year later and was replaced by John, but neither Gregory nor Benedict relinquished their claims and the result was three rival popes. Second, Constance was to address errors in the faith, in particular the movement in Bohemia led by Jan Hus. Third, the council was to reform the church hierarchy, referred to using the traditional medieval image of a reform in head and members. The council ultimately only achieved the first of these three goals, ending the schism. Jan Hus stood for trial before the council and was burned at the stake, but the Bohemian Hussites continued to grow without any official resolution on their position. The attempt to reform the church stopped with the reform of the papal head, including the election of Martin V to replace the three rival popes and the curbing of papal fiscal abuses, but never extended to the reform of the members, including the related problems of simony (purchasing of ecclesiastical offices), pluralism (bishops holding multiple bishoprics), and absenteeism (bishops residing outside of their dioceses).
The composition of the council was largely that of bishops, the most notable among them the Parisian theologians Jean Gerson and Pierre d’Ailly, and Florentine canon lawyer Francesco Zabaralla. Each of these supported the council as a means to end the papal schism and restore unity to the church, but they did not view the decrees of Constance as attempts to relegate the pope to an administrative position or to eliminate his role in the governance of the church. The primary controversy at the council occurred when John XXIII, the successor to Pisan-elected Alexander V, agreed to resign only to revoke his promise and flee Constance. The council then reached agreement with Gregory XII–the Roman pope–to convoke the council (it had previously been convoked by John XXIII), resign his office peacefully, and allow for the election of Martin V. The result was the end of the schism and the restoration of the Roman line of popes, though both John XXIII and Benedict XIII rejected the decisions of the council and maintained their right to the papal tiara.
There were two chief decrees published by the Council of Constance: Haec Sancta (1415) and Frequens (1417). Haec Sancta declared the superiority of council to pope and demanded that all the faithful, including the pope, submit to the conciliar decrees. This became particularly important at Constance, where it was used to rectify the schism by denouncing John XXIII and Benedict XII as recalcitrant, and later at the Council of Basel (1431-49), when conflict between pope and council broke out over attempts to reform the church. The basis for those reform attempts was the second chief decree of Constance, Frequens, which proposed an ongoing reform of the church through the regular convocation of general councils. The decree stated that a new general council was to convene five years after the end of Constance, then another seven years after that, followed by a council ever ten years thereafter. This mandate was fulfilled by the Council of Pavia-Sienna (1423-24) and then Basel, but another general council was not held until Lateran V (1512-1517).