In the regulatory framework for shipping, no less than for most other fields of human endeavour, it is not possible to escape the influence of public international law. One of the crucial differences between the international legal system and its national counterparts is that there is no international legislature which can enact laws binding on all States. As there is no doctrine of precedent in international law, decisions of international courts and tribunals are binding only on the parties to the actual dispute. The relevant international law is for the most part straightforward and well settled. Under customary international law, as codified in the Vienna Convention on the Law of Treaties, there are two basic modes for expressing consent to be bound, one involving a single step and the other two steps. The two-step procedure is more common for multilateral treaties and is used in the International Maritime Organization.