The Romans did not limit the study of the theory of natural law to a mere theoretical discussion, but took it further to give it practical form by transforming their rigid legal system into a living cosmopolitan law. The philosophy of natural law found expression in the Roman legal system through the division of Roman law into three distinct divisions, namely: –
The civil law called jus civile was applicable only to Roman citizens.
Jus Gentium refers to the law governing Roman citizens as well as foreigners. It consisted of universal legal principles which conformed to natural law or the law of reason.
After a passage of time, jus civile and jus gentium were both merged t o become what was called jus naturale, with Roman citizenship being extended to everyone except a few categories of people.
The Roman lawyers of that time did not consider it necessary to enter into the controversy of the conflict between positive law and natural law as long as there was a general feeling that natural law being founded on reason and conscience was superior to positive law, and therefore, in the event of a conflict between the two, the latter should be ignored.
Cicero was a great Roman lawyer, statesman and orator. According to him, the true law is good reason in agreement with nature, it is of universal application, immutable and eternal and there would not be different laws in Rome and Athens, but an eternal and immutable law which will be valid for all nations at all times.