The jurisprudence of the North Sea Continental Shelf Cases sets out the dual requirement for the formation of customary international law – State practice (objective element) and opinio juris (subjective element). It elaborated the criteria needed to establish State practice – widespread and representative participation. The case highlighted the fact that the State practice of importance were of those States whose interests were affected by the custom. It also identified the fact that uniform and consistent practice was necessary to demonstrate opinio juris – a belief that the practice amounts to a legal obligation. The North Sea Continental Self Cases also dispelled the myth that duration of the practice (i.e. the number of years) was an essential factor in the formation of customary international law.