Final answer:
Roman law was innovative in its codification, public accessibility, and principles such as legal precedents and the presumption of innocence. It underwent significant changes with the expansion of citizenship to all free men and women, and even provided protections for slaves, setting the foundation for many European legal systems.
Step-by-step explanation:
What was innovative about Roman law was the extension of citizenship and hence the reach of Roman laws following the edict of Caracalla in 212 CE, which made all free men and women in the empire citizens. This was significant as it brought almost everyone under the same legal framework and exempted these citizens from some of the harshest punishments. Additionally, Roman law was notable for being codified and made public, establishing legal precedents, and introducing the principle of a defendant being innocent until proven guilty. Even though slaves were considered property with limited legal rights, certain laws offered them protections not typically afforded to other forms of property.
The codification efforts, such as Theodosian Code and later Justinian's Corpus Juris Civilis, helped unify and streamline the legal system across the empire. Diagrams like the Twelve Tables publicly presented laws, thereby reducing potential corruption and providing a precedent for legal transparency that influenced future civilizations.