This chapter examines the distinction between public law and private law. It stresses the importance of being aware of this difference between the public/private and public law/private law dichotomies. The public–private divide is universal even if, from one society to another, it can be conceived differently in certain ways. All human communities have an idea about the relationship between the private sphere and the public domain. By contrast, the distinction between public law and private law is not universal. It may be ignored, rejected, or confined to a very limited sphere of operation as, traditionally, in common law systems. Conversely, the public law/private law distinction may be understood as an essential feature of the juridical world, as was the approach of Roman law, inherited by the continental legal systems.