Corpus Juris Civilis
Many changes had taken place within the Byzantine Empire in between Justinian and Leo VI's reign, chiefly the change in language from Latin to Greek. During Justinian's era, Latin was still in common use and Court documents were written in it. However, by the 9th century the use of Latin was obsolete, which in turn made the "Corpus Juris Civilis" code hard to use for Greek speakers, even in the capital of Constantinople. Furthermore, many of the laws within the "Corpus Juris Civilis" no longer pertained to most people, and new laws rose up to take their place. This necessitated an overhaul of the Byzantine legal system.