The survival of Novel XI until our times is not the only proof that Emperor Justinian established a new ecclesiastical province in Illyricum whose legal status was based on state law. Independent sources confirm the fact that the Archbishopric of Justiniana Prima was created in 535, which means there is absolutely no reason to question the publication and execution of this imperial constitution. The introduction of changes in 545 does not in any way influence the effective force of Novel XI with regard to the promotion of the Church of Justiniana Prima as such. We do not know how fast and by what channel the information about the establishment of this archbishopric reached Rome. However, it remais an unquestioned fact that Agapetus, the Pope at the time, interpreted Justinian's decision as stripping him of his rights and decided to clarify the matter.

An extant mention in a letter of Pope Agapetus to the Emperor, dated to 10 October 535, is of crucial importance for the confirmation of the fact that the papacy had had jurisdiction over Illyricum and that Justinian effectively established a new province. The Pope directly addressed the establishment of the Archbishopric of Justiniana Prima, but the preserved fragment of this letter gives no reason to believe that Justinian's decision led to a protest or a crisis in the relations between the Pope and the Emperor. Agapetus was probably too taken aback and surprised by the situation, which is why he only made a very diplomatic decision to send legates in order to investigate the matter. He did not directly refuse the ruler the right to make this decision nor did he initiate any discussion about the subject matter. This seems to be the most important aspect of the case. On the one hand, it was a situation without precedence for the Emperor to introduce such significant changes, conferring the rank of archbishopric to a new bishopric, especially by depriving another Church of a part of the province under its administration. On the other hand, an official copy of Novel XI was probably not available and after this law was read, a lot of ambiguity may have appeared as to the ruler's actual intentions.