It is the foundation of civil law, which is the basic legal system of most countries in Europe and South America, as opposed to the common law, which is the other major world legal system arising out of British law and applicable in England, the US and most former colonies of England.
Roman law was highly advanced for its time, and included detailed provisions for property disposition, and criminal law,etc. It is known for developing the concepts of one law for the citizens and another law for foreigners - the beginnings of Private International Law. The Emperor Justinian's Tablets of Law are a major codification of Roman law.