Advocatus diaboli
From the sixteenth century until it was abolished by the late Pope John Paul II, an advocatus diaboli (the devil's advocate") was appointed to argue against the case made by the promotor fidei (promotor of the faith, or the advocatus dei (God's advocate)) for the canonization or beatification of someone. Essentially canon law required that all arguments for and against the canonization and beatification had to be presented before the so-called "Sacred Congregaton of Rites", which was the ecclesiastical body tasked with preparing the case for presentation to the pope. Both these men were canon lawyers, essentially presenting the two sides of the case. Needless to say, when the late Pope John Paul II abolished this pratice, he effectively streamlined the procedure. John Paul II created more than five times as many saints as all his predecessors in the 20th century.