Comparative law is the study of differences and similarities between the law of different countries and, more generally, of the different legal traditions, the common law tradition, the civil law tradition and the socialist law tradition.

Several disciplines have developed as separate branches of comparative law, like comparative constitutional law and comparative civil law (in the sense of the law of torts, delicts, contracts and obligations) and comparative criminal law. Comparative civil law studies, for instance, show the law of private relations is organised, interpreted and used in different systems or countries.

Comparative law is an academic study of existing separate systems, each one analysed in its constitutive elements, how these difference elements differ in the different systems and how these elements are combined into a system. This it is different from international law both public international law and private international law though comparative law helps inform both these areas of normativity as comparative law can help international law institutions, such as those part of the United Nations System in analyzing the laws of different countries regarding their treaty obligations or in private international law when developing an approach to interpretation in a conflicts analysis.