Alexander III's election in 1159 had been disputed from the start, and Emperor Frederick Barbarossa backed a rival claimant, launching what became a schism sustained through a succession of four antipopes over nearly two decades of conflict between the papacy and the empire. The Peace of Venice in 1178 brought Frederick to formal reconciliation with Alexander, clearing the way for the council that met the following year to address the disorder the schism had left behind, chiefly the question of how to prevent a divided or disputed election from producing rival claimants again.
The council's answer, Licet de vitanda, required a two thirds majority of the cardinals present for a valid papal election, a threshold high enough that no faction controlling a bare majority could install its own candidate over serious minority objection. The rule displaced the more ambiguous earlier practice, in which acclamation by clergy, nobility and people of Rome had all been claimed at various points as a source of legitimate authority, and it gave the College of Cardinals alone the exclusive right to choose a pope, a change that removed much of the room secular rulers like Frederick had previously found to back a rival candidate of their own.