Institutes

treatise by Gaius

Also known as: “Institutiones”

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June 29, 2026

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The Institutiones, or "Institutes," by the Roman jurist Gaius, written around 161 CE, is a foundational legal text. It is divided into four books, covering the legal status of persons, property rights and inheritance, and legal actions. Gaius's work was so influential that it served as a model for the Institutes of the Byzantine emperor Justinian I, with many passages copied directly.12

The Institutiones of Gaius is unique as it is the only classical law book to survive nearly complete and unchanged through the time of Justinian. Its text was lost until 1816 when a manuscript was discovered in Verona, Italy, with St. Jerome's writings superimposed over Gaius's original words. Gaius's writings also reveal an interest in legal history, Greek philosophy, and the classification of laws.1

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Gaius
…were intended to supersede Gaius’s treatise of the same name, were modeled on the older work in style and content, and numerous passages were copied verbatim.
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…were intended to supersede Gaius’s treatise of the same name, were modeled on the older work in style and content, and numerous passages were copied verbatim.
Read More