jus gentium

noun | \ -ˈjen-shē-əm, -chəm \ | jus gen·ti·um
  1. : a body of law recognized by nations that is binding and governs their relations with each other : international law — called also law of nations

    Note: In Roman law jus gentium referred to the rules and laws that were common to the various nations or peoples under the Roman empire and were used in cases between non-Roman citizens or between a Roman and a non-Roman citizen.