Short answers, pulled from the story.
The Corpus Juris Civilis, meaning "Body of Civil Law," is a collection of fundamental legal works enacted between 529 and 534 by order of the Roman Emperor Justinian I. It has four parts: the Code, the Digest, the Institutions, and the Novellae Constitutiones.
The work was directed by Tribonian, an official in Justinian's court in Constantinople. His commission was authorized to edit, alter, and delete material from the sources it used, and the Digest drew on excerpts from 38 classical jurists.
The four parts are the Codex, a compilation of imperial pronouncements going back to the emperor Hadrian; the Digest or Pandects, completed in 533, assembling fragments from classical jurists; the Institutions, a student textbook given force of law on the 30th of December 533; and the Novellae Constitutiones, new laws passed after 534.
The Corpus became the foundation of civil law in Western Europe after being rediscovered and taught at the University of Bologna around 1070. It directly shaped the Napoleonic Code, the legal code of modern Greece, Serbian medieval law, and the canon law of the Catholic Church.
The first complete English translation was published in 1932 by Samuel Parsons Scott under the title The Civil Law. Scott's translation was later severely criticized for not using the best available Latin editions; a new English translation of the Code based on Fred H. Blume's work appeared in October 2016.
As Greek replaced Latin in the Eastern Empire, successive emperors adapted the Corpus into Greek-language codes. Emperor Leo the Isaurian issued the Ekloge ton nomon in 740, and Emperor Basil the Macedonian began the Basilika in the late 9th century, which his son Leo the Wise completed. Constantine Harmenopoulos of Thessaloniki condensed the Basilika into the six-book Hexabiblos in 1345, which was used as the first legal code of the newly independent Greek state in the 1820s.