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Becoming Catholic #43—Papal Snapshot: Papal Authority Affirmed in Emperor Justinian’s Civil Code of Law (533-34)

The “Becoming Catholic” series presents the biblical, philosophical, and historical evidence for why Eternal Christendom Founder, Joshua Charles, became and remains Catholic. The series table of contents is here.

MATTHEW 16:18-19

“And I tell you, you are Peter, and on this rock I will build my church, and the gates of Hell shall not prevail against it. I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.”

LUKE 22:31-32

“Simon, Simon, behold, Satan demanded to have you, that he might sift you like wheat, but I have prayed for you that your faith may not fail; and when you have turned again, strengthen your brethren.”

JOHN 1:42

Jesus looked at him, and said, “So you are Simon the son of John? You shall be called Cephas” (which means Peter).

JOHN 21:15-17

When they had finished breakfast, Jesus said to Simon Peter, “Simon, son of John, do you love me more than these?” He said to him, “Yes, Lord; you know that I love you.” He said to him, “Feed my lambs.” A second time he said to him, “Simon, son of John, do you love me?” He said to him, “Yes, Lord; you know that I love you.” He said to him, “Tend my sheep.” He said to him the third time, “Simon, son of John, do you love me?” Peter was grieved because he said to him the third time, “Do you love me?” And he said to him, “Lord, you know everything; you know that I love you.” Jesus said to him, “Feed my sheep.”

ACTS 15:7

Peter rose and said to them, “Brethren, you know that in the early days God made choice among you, that by my mouth the Gentiles should hear the word of the gospel and believe.”


St. Peter and Emperor Justinian I (483-565)

This “Papal Snapshot” concerns the affirmation of papal authority by the Code of Justinian (“Code”), an authoritative collection of Roman law compiled and systematized during the reign of Emperor Justinian I (483-565), who is considered a saint by the Eastern Orthodox.

Our Roadmap is as follows:

  • Our thesis is that the affirmation of papal authority in the Code of Justinian provides strong evidence of a substantially Catholic understanding of papal authority. We will show this by:
  • Providing historical context for the Code and its significance to the development of jurisprudence; then
  • Quoting substantial sections of two letters between Pope John II and Emperor Justinian I which were incorporated into the Code, and thereby made legally binding; then
  • Summarizing the conclusions we believe can be reasonably inferred from these letters.

Historical Context

The Code—often called the Civil Law—was compiled during the reign of Justinian I from 529 to 565. It consisted of four books: the Codex Constitutionum, the Digest, the Institutions, and the Novellae (or Novels in English). The Code would exercise an immense impact on the development of law throughout Europe.

What makes the affirmations of papal authority in these letters all the more remarkable is that Justinian had virtually all the earthly power to compel the Pope, and the Pope had none with which to compel him. Rome at this point was a political backwater, a city long since past its prime, and not even the capital of the barbarian kingdom of the Ostrogoths to which it belonged. Constantinople, on the other hand, was the summit of temporal power and glory. Yet it is the emperor who in his famous Code is affirming and submitting to the Pope’s authority in religious matters.

The Letters Between Pope John II and Emperor Justinian I (533-34)

In 533, Justinian wrote the Pope to obtain papal sanction for an edict he had issued outlawing various heresies. Pope John II replied in 534, confirming the law, and quoting the emperor’s letter with respect to the authority of the Roman Church. Both letters were incorporated into the Code, and thus made legally binding.1

First, let’s examine Pope John II’s letter.

The salutation immediately indicates the Pope’s authority (pg. 1149):

John, bishop of the city of Rome, to Justinian Augustus, his most glorious and most clement son.

Note that in the eyes of the Pope, the emperor is his spiritual son, and is thereby implicitly under his authority.

He continues (pgs. 1149-50):

Amid the bright praises of your Gentleness’ wisdom, most Christian of emperors, a certain constellation (so to speak) shines with purer light, because you, taught by ecclesiastical disciplines, through love for the faith and through zeal for love preserve reverence for the Roman see and to it you subject all things and you bring all things to its unity, to whose founder, that is, the first of the apostles [St. Peter], was given the command, when the Lord spoke, “Feed my sheep” (John 21:17). And that this see is truly the head of all the churches both the fathers’ regulations and the emperors’ statues declare and your Piety’s most reverent addresses testify. Therefore it is obvious that in you will be fulfilled what the Scriptures speak: “Through me kings reign and the mighty draft justice” (Prov. 8:15). For there is nought which shines with brighter light than right Faith in an emperor; there is nought which is so unable to be subject to downfall as true religion…For it is this which strengthens your sovereignty; this which preserves your rule. For the Church’s peace, religion’s unity, guards with self-grateful tranquility the sponsor of the deed who has been raised to the heights. For no little vicissitude is granted by Divine Power to him through whom the Church, divided by no wrinkles, is separated and is changed by no imported stains

The Pope makes several key observations here:

  • The emperor reverences the Roman Church, and manifests this reverence by subjecting everything to both its authority and unity;
  • The founder of the Roman Church is St. Peter, and its authority stems from this foundation;
  • Christ’s command to St. Peter in John 21:17 to “feed my sheep” is part of the biblical charge for both the first and all succeeding Popes;
  • The Roman Church is the “head of all the churches,” which has been acknowledged by both “the fathers” (i.e. the bishops) and the emperors—both spiritual and temporal powers;
  • Papal authority exists to maintain the Church’s peace, its unity, and the purity of the Christian Faith.

He continues (pg. 1150):

Accordingly your Serenity’s letter we have received…by whose report also we have learned that to your faithful peoples you have proclaimed an edict through love for the faith for the intention of the heretics to be removed, according to apostolic doctrine, by the intervening consent o four brethren and fellow-bishops. And this, because it agrees with apostolic doctrine, by our authority we confirm.

Moreover, the text of the letter is as follows.

The Pope, after confirming the emperor’s edict per his request, then quotes the emperor’s letter to him, which is likewise quite fulsome in its affirmation of papal authority. We will once more proceed (roughly) paragraph by paragraph.

Justinian opens with an unequivocal affirmation of papal authority (pgs. 1150-51):

Paying honor to the apostolic see and to your Sanctity (which ever has been and is in our prayer), as becomes those honoring as a father your Beatitude, we hasten to bring to your Sanctity’s knowledge all matters which pertain to the churches’ status, since ever it has been our great desire that the unity of your apostolic see and the status of God’s holy churches should be maintained, which status thus far continues and undisturbedly persists, because no opposition interposes. And so we have hurried both to subject and to unite to your Sanctity’s see all bishops of the whole eastern region.

Note several key assertions by Justinian:

  • As the Pope calls the emperor his son, so the emperor calls the Pope his father;
  • The Roman Church is entitled to be informed of everything affecting the churches throughout the world, particularly in the east;
  • The Roman Church is the keystone of unity for the Catholic Church; and
  • The eastern bishops ought to be submitted to the authority of the Pope, and the emperor will endeavor that they are.

These assertions—by an emperor considered a saint by the Eastern Orthodox, no less—are thoroughly Catholic in tone and substance.

The same theme persists in the next paragraph, except now applied to doctrinal authority (pg. 1151):

And at present, therefore, we have thought necessary that the matters which here are disturbed, although they are clear and undoubted and always maintained firmly and proclaimed by all bishops according to your apostolic see’s doctrine, should come to your Sanctity’s knowledge. For we do not permit that anything which pertains to the churches’ status, although it is clear and undoubted, and which is set in motion should not become known also to your Sanctity, because it is the head of all the holy churches. For by all means—as has been said—we hasten to increase your see’s honor and authority.

Once more, Justinian affirms that the Roman Church is the “head of all the holy churches.” In addition to this, he affirms that all bishops proclaim the faith “according to your apostolic see’s doctrine,” and that he desires to increases the honor and authority of the Roman Church.

He continues by affirming the Roman Church’s general doctrinal authority, its essential role in maintaining the unity of the Church, and its doctrinal authority as manifested through the previous ecumenical councils (pg. 1151-52):

Therefore we make known to your Sanctity that certain few persons, unbelieving and alien from God’s Holy Catholic and Apostolic Church, have dared in Jewish fashion to speak against those matters which by all bishops according to your doctrine are held rightly and praised and proclaimed [creedal formula]…But all the bishops of the Holy Catholic and Apostolic Church and the most reverend archimandrites of the sacred monasteries, following your Sanctity and maintaining the status and the unity of God’s holy Churches, which unity they have in regard to your Sanctity’s apostolic see, changing nothing at all about the ecclesiastical status which hitherto has obtained and obtains, by one consent confess and praise, proclaiming [creedal formula]…

Moreover we receive four holy councils, that is, of the 318 holy fathers who assembled in Nicaea, and of the 150 holy fathers who convened in this royal city [Constantinople] and of the holy fathers who assembled first in Ephesus and of the holy fathers who convened in Chalcedon, just as your apostolic see teaches and proclaims.

Therefore all bishops, following your apostolic see’s doctrine, so believe and confess and proclaim.

Wherefore we have hastened to bring these matters to your Sanctity’s knowledge by Hypatius and Demetrius, the most blessed bishops, that the things which by a certain few monks have been denied evilly and in Jewish fashion according to Nestorius’s disbelief may not escape your Sanctity’s notice.

The emperor asserts that “all bishops” follow the doctrine of the Roman Church.

He concludes (pgs. 1152-53):

Therefore we ask your paternal Affection that by your letters, sent to us and to the most holy bishop and patriarch, your brother, of this genial city [Constantinople], since he himself has written by the same persons to your Sanctity, hastening in all matters to follow your Beatitude’s apostolic see, you should make known to us that your Sanctity receives all who confess rightly the aforesaid things and condemns the disbelief of those who in Jewish fashion have dared to deny the right faith. For thus both all persons’ love for you and your see’s authority increase the more and the unity of the holy churches—which is your concern—will be preserved undisturbed, when all the most blessed bishops shall have learned through your Sanctity’s sincere doctrine of the matters which have been referred to you.

Moreover we ask your Beatitude to pray for us and to seek for us God’s providence.

And by another hand [the emperor’s subscription]: May the Divinity guard you for many years, holy and most religious father.

From this, we see that the emperor once again stresses the authority of the Roman Church in matters of doctrine and unity, declaring that the unity of the Church is a unique concern of the Roman Church, and that the bishops wait to hear the Pope’s decision on those teachings (presumed heretical) which have been submitted to his judgment. Indeed, the Pope’s communion is the Catholic communion.

Pope John’s reply—contained in the original letter in which he transcribed Justinian’s letter to him—is likewise revealing. He begins (pg. 1153):

Therefore, most glorious emperor, it is clear—as the tenor of the reading and your legates’ report reveals—that you are desirous for apostolic instructions, when about the Catholic religion’s faith you understand these things, you have written these things, which—as we have said—both the apostolic see teaches and the fathers’ venerable authority has decreed and we have confirmed in all points.

Therefore it is fitting for the faithful to write these things in the tables of the heart, to keep these things as the pupils of the eyes, for there is not anyone, in whom Christ’s love burns, who can be an opponent to the faith of your so right, so true confession, since in damning the impiety of Nestorius and of Eutyches obviously and of all heretics you preserve unshakenly and inviolably and with a mind pious and devoted to God the one, true, Catholic faith of our Lord and God, instituted by the Savior Jesus Christ’s instruction and diffused everywhere by prophetic and apostolic preachings and strengthened by the saints’ confessions throughout the whole world, unified by the fathers’ and the teachers’ opinions and consistent with our teaching

This, therefore, is your true faith, this the sure religion, this all the fathers of blessed memory and the Roman Church’s heads, whom in all things we follow, this the apostolic see has proclaimed hitherto and indestructibly has guarded: whoever has existed as a contradictor to this confession, to this faith, he himself has judged himself to be alien from the Holy Communion, alien from the Catholic Church

Here, we simply note that in addition to repeating many of his previous assertions about papal authority, Pope John II is likewise explicit that the Roman Church has maintained the truth faith in its entirety, and that its teaching is binding on all, to the extent that whoever contradicts it has become alien to the Catholic Church itself. Thus, to be Catholic is to be submitted to the teaching of the Roman Church, a proposition the emperor himself quite clearly believed.

The Pope continues (pg. 1154):

Moreover the first of the apostles [St. Peter] through us to them not believing [heretics] speaks the words of the Prophet Isaiah: “Walk in the light of your fire and of the flame, which you have kindled” (Isa. 50:11), but their heart was hardened, as it is written, that they might not understand and the sheep, which were not mine, wished not to hear the shepherd’s voice [cf. Mark 4:10; John 10:26-27]. And since in these matters they maintained the things which have been ordained by their pontiff, we have not at all received them in our communion and we have ordered them to be alien from every Catholic church, unless, since their error has been damned, they shall have signified, after a canonical profession has been made, that they will follow our teaching as speedily as possible. Surely it is fair that those who do not adapt at all their obedience to our ordinances should be considered banished from the churches. But because the Church never closes her bosom to returners, I beg your Clemency that if, when their previous error has been discarded and when their wicked intention has been removed, they shall have wished to return to the Church’s unity, you would remove the stings of your indignation from them, when received in our communion, and grant the pardon of a kindly spirit to us making intercession.

Moreover we beseech God and our Savior Jesus Christ that he should deign to guard you for long and peaceful times in this true religion and unity and veneration for the apostolic see, whose preeminence you, as most Christian and pious, preserve in all matters

And by another hand: The grace of our Lord Jesus Christ and the love of God and the communion of the Holy Spirit be always with you, most pious son.

Likewise the subscription: May Almighty God guard your rule and safety with perpetual protection, most glorious and most clement son, Emperor Augustus.

In this conclusion of his response to the emperor, the Pope once more makes several important affirmations:

  • The foundation of his authority is the authority of St. Peter granted to him by Christ;
  • The Pope is Christ’s earthly “shepherd” (namely, the chief shepherd, since all priests are shepherds);
  • The communion of the Pope is the communion of the Catholic Church, and the Pope has the authority to declare dissenters alien to that Catholic Church—an authority that all local Catholic churches must obey;
  • The communion of the Pope is the communion in which one maintains the unity of the Catholic Church;
  • The Roman Church is preeminent “in all matters” related to the Church, which the emperor himself has acknowledged;
  • The emperor is the “son” of the Pope, and thus his subject in religious matters.


As the foregoing letters show, Pope John II and Emperor Justinian I affirmed papal authority in the strongest, and indeed deeply Catholic terms. They affirmed:

  • The Roman Church was founded by St. Peter, and owes its unique authority to the command of Christ Himself;
  • The Pope is the chief shepherd;
  • The Pope is the spiritual father of the emperor, his spiritual son;
  • The Roman Church is the head of all the churches, such that it is preeminent “in all matters”;
  • The Roman Church possesses supreme doctrinal authority, namely the authority to teach the whole Church, and require all Catholic churches to adhere to its judgments to be considered “Catholic”;
  • Papal authority has been acknowledged by both the “fathers” (i.e. the bishops) and the emperors;
  • The Roman Church is the keystone of the unity of the Catholic Church, and has a unique responsibility with regard to this unity;
  • The communion of the Pope is the communion of the Catholic Church—to be outside of it is to be outside the Church;
  • The Roman Church is entitled to be informed about everything that affects the state of the churches;
  • The emperor believes it his duty to ensure all the bishops—including those in the east—are subject to the authority and unity of the Roman Church, and thus the Catholic Church.


  1. Pope John II, Letter to Emperor Justinian I (533-34); P.R. Coleman-Norton, ed., Roman State & Christian Church: A Collection of Legal Documents to A.D. 535, Volume 3 (Eugene, OR: Wipf & Stock, 2018), 1149-54. ↩︎
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