1. common lawLaw, etc. term
2. customary law (in international law)Law, etc. term
Wikipedia definition
3. Custom (law)Custom in law is the established pattern of behavior that can be objectively verified within a particular social setting. A claim can be carried out in defense of "what has always been done and accepted by law. " Customary law exists where: a certain legal practice is observed and the relevant actors consider it to be law. Related is the idea of prescription; a right enjoyed through long custom rather than positive law.
Read “Custom (law)” on English Wikipedia
Read “慣習法” on Japanese Wikipedia
Read “Custom (law)” on DBpedia


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