Rules of international law may sometimes conflict with one another; therefore, it is important to find out which rules should prevail under such circumstances. In other words, the hierarchy of norms among the sources of international law should be determined. “In theory, there is no hierarchy among the three sources of law listed in Article 38 of the International Court of Justice Statute. In practice, however, international lawyers usually look first to any applicable treaty rules, then to custom, and last to general principles”.