Where did this idea come from? Ancient Rome? - natural law- or universal divine law derived from right reason. The Romans came to view their law of nations as derived from or identical to this natural law, thus giving Roman jurists a philosophical justification for systematizing Roman law according to basic principles. Source: Western Civilization Volume I: To 1715 Eigth Ed. Jackson J. Spielvogel Is it all that surprising that the same civilization that gave us the separation of powers also gave us our legal system and the concept of natural law? Is it all that surprising that around that time Rome came up with the idea of natural rights, Roman Emperor Caracalla made every free citizen in the Empire a Roman citizen? Thoughts?