The interest theory of public law emerges from the work of Roman jurist Ulpian, who stated ""Publicum ius est, quod ad statum rei Romanae spectat, privatum quod ad singulorum utilitatem." (Public law is that, which concerns Roman state, private law is concerned with the interests of citizens.) Charles-Louis Montesquieu elaborates upon this theory in "The Spirit of the Laws", published during the 18th century, wherein Montesquieu establishes a distinction between international (right of nations), public (political right), and private (civil right) law according to various actors interests and rights. There, he writes: “Considered as inhabitants of a planet so large that different peoples are necessary, they have laws bearing on the relation that these peoples have with one another, and this is the . Considered as living in a society that must be maintained, they have laws concerning the relation between those who govern and those who are governed, and this is the . Further, they have laws concerning the relation that alI citizens have with one another, and this is the .”