Papal selection before 1059
The selection of the Pope, the Bishop of Rome and Supreme Pontiff of the Catholic Church, prior to the promulgation of In Nomine Domini in AD 1059 varied throughout history. Popes were often putatively appointed by their predecessors or by political rulers. While some kind of election often characterized the procedure, an election that included meaningful participation of the laity was rare, especially as the Popes' claims to temporal power solidified into the Papal States. The practice of papal appointment during this period would later result in the putative jus exclusivae, i.e., the claimed but invalid right to veto the selection that Catholic monarchs exercised into the twentieth century.
The absence of an institutionalized procedure of papal succession facilitated religious schism, and the Catholic Church currently regards several papal claimants before 1059 as antipopes. Further, the frequent de facto requirement of political approval of elected popes significantly lengthened periods of sede vacante, i.e., transitional vacancy of the papacy, and weakened it. In 1059, Pope Nicholas II succeeded in limiting future papal electors to the College of Cardinals in In Nomine Domini, instituting standardized papal elections that eventually developed into the procedure of the papal conclave.