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Why was the Institutes written during Justinian I’s legal reforms?

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Mosaic detail of Emperor Justinian I with a jeweled crown and halo, wearing ornate robes, from the Church of San Vitale in Ravenna, Italy. — Justinian I Justinian I, detail of a mosaic in the Church of San Vitale, Ravenna, Italy.

The Institutes (or Institutiones) were written during the legal reforms of Justinian I to serve as an elementary textbook or outline of legal institutions for first-year law students.1

Published in 533 CE under the supervision of the jurist Tribonian, the work was designed to provide a foundational understanding of the law as it was being reorganized into the Corpus Juris Civilis. The Institutes were modeled in both style and content after the earlier, authoritative treatise of the same name written by the Roman jurist Gaius, with many passages copied verbatim to ensure continuity in legal education. By creating this accessible summary, Justinian provided a necessary educational companion to the more complex Digest and Codex Constitutionum, ensuring that the newly clarified legal system could be effectively taught and understood.213