MOre correctly, he is the final judge for every issue, and always has been. The heretic Montanus appealed from the bishop of Antioch (a future patriarchal see) to the bishop of Rome, and that was in about 170AD. At the same time, Irenaeus of Lyons, who came originally from the Antiochene area, declared that the Church of Rome had the highest rank. For a less obvious but, to my mind, more convincing proof, look at the letters of Ignatius of Antioch, unmistakeably dated to 100AD, and notice how differently he treats Rome from every other see. With Tralles, Ephesus, Magnesia, he is confident, authoritative and assertive, as the bishop of great Antioch might well be expected to be; with Rome, and Rome alone, he is humble and respectful. Finally, there is the emperor Gallienus' (I think) sentence in the matter of Paul of Samosata and the schism in Antioch. Asked to rule on the legitimacy of two rival claimants to the Antiochene episcopal throne, Gallienus, no friend to the Church, and one who would welcome, if he could provoke it, a violent break-up in the Christian body, nevertheless ruled that there could be only one Bishop, and that the legitimate one was the one who was in communion with the Bishops of Italy (read: Rome and environs; the reason why he said "Italy" may well be that there still were a few bishops of the Novatian schism around, and one of them would certainly be claiming the title of Rome, however ineffectually - but the bishops of Italy had always been in communion with the legitimate Pope). When asked to rule on the quarrels of a particular body, it was standard Late Roman practice to investigate what was the suum ius, the lnternal rule, of that body, and rule accordingly. There is a famous case when the Emperor Constantine demanded to have the laws of an insignificant Anatolian township called Orcristum copied and sent to him so he could rule on an appeal case. So we have to conclude that the universal power of appeal of the Roman see is very ancient indeed. And it was the Council of Sardica, as early as 352, that ruled that Rome alone had the right to try bishops; one century later, St.Patrick appealed to Rome against the condemnation he had suffered from British bishops, and was triumphantly probatus by Leo I the Great, according to his own testimony and to Irish annalistic sources.