Rome began considering the case against Luther again in early 1520. After Luther’s unproductive meetings with Cardinal Cajetan and papal ambassador Karl von Miltitz, the matter had taken a secondary role to questions over the election of a new emperor. With Charles I of Spain elected, Rome was now free to resume the proceedings against Luther. One significant catalyst for renewed attention was the Leipzig Debate in the summer of 1519, where Luther effectively denied papal authority over dogma and suggested that pope and council could err. This was reported to Rome by his interlocutor, John Eck, and intensified the proceedings.
In several meetings during the winter months of 1520, the case against Luther began to take shape. A consultation that included Cajetan was formed in February and began to detail Luther’s errors, though distinguishing between his teaching and his person. This would provide room to recant rather condemning him personally. However, upon John Eck’s arrival in April, the prosecution shifted toward a more direct reproach. It was Eck who informed the committee of Luther’s new attitude toward the papacy. It was also Eck who would draft a list of forty-one doctrinal errors that the consultation incorporated into the original draft form of a bull against Luther. This would eventually lead to the papal bull Exsurge Domine, threatening Luther with excommunication if he did not come to Rome and recant.
In Wittenberg, Luther was still relying on the protection of Frederick the Wise. With the election and pending coronation of Charles V, Frederick had lost some of his bargaining power with Rome, as well as his status as “imperial vicar” during the interregnum. For the elector, there was the possibility that he and his university might be excommunicated or even receive the imperial interdict if he were found guilty of harboring a noted heretic. During this period, he sought the legal opinion of his jurists and laid the groundwork for how he might defend himself against the accusation.