Customary Law A legal custom is an established pattern of behavior within a social situation that can be objectively confirmed. In support of "what has always been done and approved by law," a claim can be made. There is customary law (also known as consuetudinary or unofficial law) where: A specific legal procedure is followed, and It is regarded as law by the relevant actors (opinio juris). The majority of customary laws deal with community standards that have been in place for a long time in a certain location. However, the phrase can also refer to areas of international law where particular criteria have been widely accepted as appropriate bases of action — for example, anti-piracy or anti-slavery legislation (see hostis humani generis). Customary laws will have supportive court judgments and case law that has grown over time to give further weight to their rule as law and also to give additional weight to their rule as law. Customary law is a term used in international