The Codex Theodosianus was a compilation of the laws of the Roman Empire under the Christian emperors since 312. A commission was established by Theodosius II in 429 and the compilation was published in the eastern half of the Roman Empire in 438. One year later, it was also introduced in the West by the emperor Valentinian III.
On March 26, 429, Emperor Theodosius II announced to the senate of Constantinople his intentions to form a committee to codify all of the laws (leges, singular lex) from the reign of Constantine up to Theodosius II and Valentinian III. Twenty-two scholars, working in two teams, worked for nine years starting in 429 to assemble what was to become the Theodosian Code. Their product was a collection of 16 books containing more than 2,500 constitutions issued between 313 and 437. John F. Matthews illustrates the importance of Theodosius' Code when he said, "the Theodosian Code was the first occasion since the Twelve Tables on which a Roman government had attempted by public authority to collect and publish its leges." The code covers political, socioeconomic, cultural and religious subjects of the 4th and 5th century in the Roman Empire.
A collection of imperial enactments called the Codex Gregorianus had been written in 291 and the Codex Hermogenianus, a limited collection of rescripts from 293-294, was published. Theodosius desired to create a code that would provide much greater insight into law during the later Empire (321-429). According to Peter Stein, "Theodosius was perturbed at the low state of legal skill in his empire of the East." He apparently started a school of law at Constantinople. In 429 he assigned a commission to collect all imperial constitutions since the time of Constantine. The laws in the code span from 312-438, so by 438 the "volume of imperial law had become unmanageable" During the process of gathering the vast amount of material, often editors would have multiple copies of the same law. In addition to this, the source material the editors were drawing upon changed over time. Clifford Ando notes that according to Matthews, the editors "displayed a reliance on western provincial sources through the late 4th century and on central, eastern archives thereafter."
After six years an initial version was finished in 435, but it was not published, instead it was improved upon and expanded and finally finished in 438 and taken to the Senate in Rome and Constantinople. Matthews believes that the two attempts are not a result of a failed first attempt, but instead the second attempt shows "reiteration and refinement of the original goals at a new stage in the editorial process." Others have put forth alternate theories to explain the lengthy editorial process and two different commissions. Boudewijn Sirks believes that "the code was compiled from imperial copy books found at Constantinople, Rome, or Ravenna, supplemented by material at a few private collections, and that the delays were caused by such problems as verifying the accuracy of the text and improving the legal coherence of the work."
Context of Code 
The Code was written in Latin and incorporated the terms Constantinopolitana and Roma for Constantine's capital and for the original capital in Italy. It was also concerned with the imposition of orthodoxy - the Arian controversy was ongoing - within the Christian religion and contains 65 decrees directed at heretics.
Originally, Theodosius had attempted to commission leges generales beginning with Constantine to be used as a supplement for the Codex Gregorianus and the Codex Hermogenianus. He intended to supplement the legal codes with the opinions and writings of ancient Roman Jurists, much like the Digest found later in Justinian's Code. But the task proved to be too great, and in 435 it was decided to concentrate solely on the laws from Constantine to the time of writing. This decision defined the greatest difference between the Theodosian Code and Justinian's later Corpus Juris Civilis.
John F. Matthews observes, "The Theodosian Code does, however, differ from the work of Justinian (except the Novellae), in that it was largely based not on existing juristic writings and collections of texts, but on primary sources that had never before been brought together." Justinian’s Code, published about 100 years later, comprised both ius, "law as an interpretive discipline", and leges, "the primary legislation upon which the interpretation was based." While the first part, or Codex, of Justinian’s Corpus Civilis Juris contained 12 books of constitutions, or imperial laws, the second and third parts, the Digest and the Institutiones, contained the ius of Classical Roman jurists and the Institutes of Gaius.
While the Theodosian Code may seem to lack a personal facet due to the absence of judicial reviews, upon further review the legal code can give us insight into Theodosius' motives behind the codification. Lenski quotes Matthews as noting that the "imperial constitutions represented not only prescriptive legal formulas but also descriptive pronouncements of an emperor’s moral and ideological principles." Apart from clearing up confusion and creating a single, simplified and supercedent code, Theodosius II was also attempting to solidify Christianity as the official religion of the Empire, begun under Constantine's rule. In his City of God, St. Augustine praised Theodosius the Great, Theodosius II's grandfather, who shared his faith and devotion to its establishment, as "a Christian ruler whose piety was expressed by the laws he had issued in favor of the Catholic Church."
Books 1-5 lack the level of manuscript support available for books 6-16. The first five books of the surviving Codex draw largely from two other manuscripts. The Turin manuscript, also known as "T," consists of 43, largely discontinuous folios. The second manuscript is a Breviarium, and a good part of the Breviarium that is included in book 1 actually contains the original text of the respective part of the original codex. The latter part of the Codex, books 6-16, drew largely from two texts as well. Books 6-8 of the Codex were preserved in the text of a document known as Parsinus 9643. The document circulated early medieval French libraries, as well as the other formative document for the latter part of the code, a document held in the Vatican (Vat. Reg. 886), also known as "V". Scholars consider this section to have been transmitted completely.
English Translation 
- LacusCurtius • Roman Law — Theodosian Code (Smith's Dictionary, 1875)
- Sirks, A. J. B., The Theodosian Code, a Study (Editions du Quatorze Septembre, 2007) ISBN 978-3-00-022777-6
- Lenski, pg. 337-340
- Matthews, p. 17
- Matthews, pg. 10-18
- Peter Stein, pp. 37-38
- Susan Martin, p. 510
- Clifford Ando, p. 200
- Michael Alexander, p. 191
- Michael Alexander, p. 191-193
- Tituli Ex Corpore Codici Theodosiani
- Mango, Cyril, Oxford History of Byzantium (Oxford: 2002) pp 105
- Matthews, p. 12
- Matthews, pp. 10-12
- Lenski, pg. 331
- Matthew, p. 8
- Matthews, pp. 87
- Matthews, pp. 86
- Clyde Pharr (in collaboration with Theresa S. Davidson and Mary B. Pharr), The Theodosian Code and Novels and the Sirmondian Constitutions, a Translation with a Commentary, Glossary and Bibliography (1952). For a description of how this project was carried out, see Linda Jones Hall, "Clyde Pharr, the Women of Vanderbilt, and the Wyoming Judge: the Story behind the Translation of the Theodosian Code in Mid-Century America, 8 Roman Legal Tradition 1, 3 (2012), available at http://romanlegaltradition.org/contents/2012/RLT8-JONESHALL.PDF. See also Timothy Kearley, "Justice Fred Blume and the Translation of Justinian's Code," 99 Law Library Journal 525, 536-545 (2007), available at https://uwacadweb.uwyo.edu/blume&justinian/HistoryAJCrev-1.pdf
- ACTI. Auxilium in Codices Theodosianum Iustinianumque investigandos, Iole Fargnoli (cur.), LED Edizioni Universitarie, Milano 2009, ISBN 978-88-7916-403-0
- Alexander, Michael C. (Spring 1995). "Review: The Theodosian Code by Jill Harries; Ian Wood". Law and History Review (University of Illinois Press) 13 (1): 190–192.
- Buckland, W. W. (1993). A Textbook of Roman Law from Augustus to Justinian. Cambridge: Cambridge University Press. pp. 37–38.
- Lenski, Noel (February -March , 2003). "Review: Laying Down the Law. A Study of the Theodosian Code by John Matthews". The Classical Journal (The Classical Association of the Middle West and South, Inc.) 98 (3): 337–340.
- Martin, Susan D. (October , 1995). "Review: The Theodosian Code by Jill Harries; Ian Wood". The American Journal of Legal History (Temple University) 39 (4): 510–511.
- Matthews, John F. (2000). Laying Down the Law: A Study of the Theodosian Code. New York, NY: Yale University Press.
- Tellegen-Couperus, Olga (1993). A Short History of Roman Law. New York, NY: Routledge. pp. 138–141.
- Codex Theodosianus. Liber V - Le Code Théodosien, Livre V. Texte latin d'après l'édition de Th. Mommsen. Traduction française, introduction et notes. Éd. par Sylvie Crogiez, Pierre Jaillette, Jean-Michel Poinsotte. Turnout, Brepols, 2009 (Codex Theodosianus - Le Code Théodosien (CTH), vol. 5).
- Primary sources:
- Codex Theodosianus (Latin), ancientrome.ru.
- Codex Theodosianus (Latin) (only books 1-9), Ed. Mommsen, Meyer, & Krueger (Latin). Website upmf-grenoble.fr.
- (English) A list of imperial laws of 311 until 431 contains summaries of many laws involving religion from the Theodosian code and other sources, in chronological order.
- (English) Codex Theodosianus XI-7-13; XV-5-1, -12-1; XVI-1-2, -5-1, -5-3, -7-1, -10-4 (on Religion), English translation Oliver J. Thatcher e.a., 1907. Website fordham.edu.
- Secondary sources:
- Article by George Long, M.A., Fellow of Trinity College, on the Codex Theodosianus, in A Dictionary of Greek and Roman Antiquities, John Murray, London 1875.