It is the foundation of Civil law, which is the basic legal system of most countries in Europe and South America. It has also influenced the Common law, another major world legal system arising out of English law which is applicable to the United Kingdom, apart from Scotland, to the United States, apart from Louisiana, and to most former British colonies.
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 arranged for the modernisation of most of Roman law in his Code and his Pandectae a fifty book set which took three years to compile and was completed in 533. The emperor also ordered the production of a textbook, Iustiniani Institutiones, (the Justinian teaching manual), during the early 530s. It was intended as an overview of Roman law for legal students and consisted of just four books. This work has been called the most influential law book ever written as it has been on the reading list for legal students in countries using Civil law for nearly 1500 years so far.