Ozment, Steven E. The Age of Reform: 1250-1550 : An Intellectual and Religious History of Late Medieval and Reformation Europe. New Haven, Conn. ; London: Yale University Press, 1980. Kindle Electronic Edition.
Chapter 4, “The Ecclesiopolitical Traditions” pp. 135-181 Part 4, “The Schism and the Rise of the Conciliar Theory of Church Government” pp. 155-164
Ozment now moves us to 1414 when a council met in the Swiss city, Constance. The council was the result of a schism which began in 1378 (Ozment 1980, 155). By 1414 there were three popes in three cities, all with cardinals and political supporters. In their decree they asserted as a duly assembled council over the Roman church to have authority over the selection of the Pope (Ibid., 156). The issue of the election of deposition of a Pope had become politically charged over the centuries. Ozment observes it was also a psychological difficulty. “Medieval people attached great importance to orderly succession in both ecclesiastical and political office; the deposition of a duly elected pope seemed as unthinkable as the execution of a duly crowned king” (Ibid., 159). There were some precedents for condemnation of a pope, but it was a very serious matter, normally requiring heresy, though some would include obvious sin (Ibid., 161).