Why did Justinian order a major compilation of Roman laws after becoming Byzantine emperor?

When Emperor Justinian I ascended the throne in 527 CE, he found the Roman law in a state of profound confusion and disarray. The legal system was divided into two masses—"old law" and "new law"—that were characterized by significant issues:1

• Inconsistency and Contradiction: The existing statutes, senatorial decrees, and juristic writings were often contradictory, and the imperial ordinances (constitutions) were numerous and disorganized.1
• Inaccessibility: Many legal records had been lost, were of doubtful authenticity, or were so scarce that even public libraries lacked complete collections.1
• Inefficiency: The sheer volume and complexity of the material made the law difficult to navigate and costly to apply.1

Justinian sought to promote the well-being of his subjects by providing easily accessible justice and rooting out corruption. To achieve this, he commissioned a comprehensive codification to purge inconsistencies, eliminate obsolete provisions, and create a unified, binding corpus. This monumental effort, supervised by the legal authority Tribonian, resulted in the Corpus Juris Civilis, which became the definitive legal foundation for the Roman world.21