The Corpus Juris Civilis ('Body of Civil Law') is the massive codification of Roman law commissioned by Emperor Justinian I.

The project's goal was to systematize and preserve centuries of Roman legal thought into a single, comprehensive work.

It was compiled in the 6th century CE by a commission of jurists led by Tribonian.

The work consists of four main parts.

The first part, the 'Codex,' was a collection of all existing imperial laws.

The second part, the 'Digest' or 'Pandects,' was a summary of the writings of great Roman legal scholars.

The third part, the 'Institutes,' served as a textbook for law students.

The fourth part, the 'Novellae' or 'Novels,' contained the new laws passed by Justinian himself.

The Corpus Juris Civilis was written primarily in Latin, though the Novellae were mostly in Greek.

It was rediscovered in Western Europe in the Middle Ages and became the foundation of most modern civil law systems.