Actually, and hopefully this is the last time I have to bring this up, (but I know that people being people will just keep throwing this chestnut out there, ignorantly), this is a false quote from Augustine, and probably just a twisted paraphrase, that is oft repeated by Catholics that have not a clue...
"Roman Catholic scholar Klaus Schatz, S.J., addressed this quote in, Papal Primacy (Minnesota: The Liturgical Press, 1996, p. 34-35). Schatz, received his doctorate at Rome's Gregorian University in 1974 and since 1975 has taught Church history at the St. Georgen School of Philosophy and Theology in Frankfurt, Germany. Schatz is not fringe Catholic scholar. He believes in the development of the papacy."
[The following is from Dr. Schatz's book...]
“In the case of North Africa it is interesting to note the attitude of a self-confident and organizationally intact Church toward Rome. The saying of Bishop Augustine of Hippo (396-430), Roma locuta, causa finita ("Rome has spoken, the matter is settled") was quoted repeatedly. However, the quotation is really a bold reshaping of the words of that Church Father taken quite out of context.
Concretely the issue was the teaching of Pelagius, an ascetic from Britain who lived in Rome. Pelagius took a stand against permissive and minimalist Christianity that shrank from the moral seriousness of Christian discipleship and used human incapacity and trust in grace alone to excuse personal sloth. He therefore emphasized an ethical Christianity of works and moral challenge for which grace was primarily an incentive to action; human beings remain capable of choosing between good and evil by their own power. This teaching was condemned by two North African councils in Carthage and Mileve in 416. But since Pelagius lived in Rome, and Rome was the center of the Pelagian movement, it seemed appropriate to inform Pope Innocent I of the decision. Ultimately, the struggle against Pelagianism could only be carried on with the cooperation of Rome. The Pope finally responded in 417, accepting the decisions of the two councils. Augustine then wrote: "In this matter, two councils have already sent letters to the apostolic see, and from thence rescripts have come back. the matter is settled (causa finita est); if only the heresy would cease!"
This was found at Beggars All blog
Note that the Pope had to be told what to think on the matter. So much for his divinely guided infallibility...
Interesting, although that is not how it is explained by the writings that we have of the time... You make it sound as if the synods acted on their own and merely INFORMED the Pope of their actions. Hardly...
The new acquittal of Pelagius did not fail to cause excitement and alarm in North Africa, whither Orosius had hastened in 416 with letters from Bishops Heros and Lazarus. To parry the blow, something decisive had to be done. In autumn, 416, 67 bishops from Proconsular Africa assembled in a synod at Carthage, which was presided over by Aurelius, while fifty-nine bishops of the ecclesiastical province of Numidia, to which the See of Hippo, St. Augustine's see belonged, held a synod in Mileve. In both places the doctrines of Pelagius and Caelestius were again rejected as contradictory to the Catholic faith. However, in order to secure for their decisions "the authority of the Apostolic See", both synods wrote to Innocent I, requesting his supreme sanction. And in order to impress upon him more strongly the seriousness of the situation, five bishops (Augustine, Aurelius, Alypius, Evodius, and Possidius) forwarded to him a joint letter, in which they detailed the doctrine of original sin, infant baptism, and Christian grace (St. Augustine, "Epp. clxxv-vii"). In three separate epistles, dated 27 Jan., 417, the pope answered the synodal letters of Carthage and Mileve as well as that of the five bishops (Jaffé, "Regest.", 2nd ed., nn. 321-323, Leipzig, 1885). Starting from the principle that the resolutions of provincial synods have no binding force until they are confirmed by the supreme authority of the Apostolic See, the pope developed the Catholic teaching on original sin and grace, and excluded Pelagius and Caelestius, who were reported to have rejected these doctrines, form communion with the Church until they should come to their senses (donec resipiscant). In Africa, where the decision was received with unfeigned joy, the whole controversy was now regarded as closed, and Augustine, on 23 September, 417, announced from the pulpit (Serm., cxxxi, 10 in P. L., XXXVIII, 734), "Jam de hac causa duo concilia missa sunt ad Sedem apostolicam, inde etiam rescripta venerunt; causa finita est". (Two synods having written to the Apostolic See about this matter; the replies have come back; the question is settled.)
http://www.newadvent.org/cathen/11604a.htm
Apparently, the good "Roman catholic scholar" has not given us the entire story. Yes, the actual words are a "paraphrase - but they say the same thing. By examing these letters, one can conclude that the synods desired the "force of an Apostolic See" to settle the matter - as two synods before Mileve proved unsuccessful in routing out the heresy. The good people of Africa responded with JOY at the decision from the See. Augustine himself notes that the matter is settled.
The words attributed to St. Augustine are shown above, and in context. What can we learn from this? That Roman Catholic scholars are not infallible. And that people of the 400's highly regarded the position of the Pope and his decisions.
Regards