Una gran medida de ‘opinio juris’ y práctica estatal al gusto: ¿la receta de la costumbre internacional contemporánea?

The social practice of contemporary international law does not correspond fully to the practice that existed at the time of establishment of the ICJ. The world of 1945 is definitely not the same as the twenty-first century. This reality has undoubtedly become international law and each of its vertebral components, including the theory of sources and their types.From this perspective, this research seeks to revise the traditional concept of international custom by studying its two ingredients, in particular the opinio juris, which will be tested through the use of contemporary legal literature and jurisprudence. After exposing some of the greatest difficulties of the classical concept of opinio juris, will be a presentation of new and current concepts of it. This will show if in fact a development of the classic definition of the opinio juris required and if you can suggest that this is the only required ingredient in the recipe of contemporary international custom.