There have been, however, many instances under traditional international legal theory when a state's consent has not been required. Professor Brierly, in a trenchant critique, has stated that consent as the basic concept of obligation under customary international law has involved no more than the use of a legal fiction. Moreover, the traditional notion of consent in treaty law has stated that any form of coercion on the state does not invalidate a treaty; freely given consent is not required. Furthermore consent by new states to existing rules of customary international law has been implied regardless of any actual consent. The positivist theorists have presumed that the states which came into existence in 1919 implicitly consented to the existing international law when committing their first state acts.
More recently, however, the Afro-Asian states that have come into existence since 1945 have challenged this traditional notion of consent that obligates states to observe rules of international law to which they have never actually consented. These states, as well as the Latin American and Communist states, have also objected to those legal rules that do not require freely given consent as a prerequisite to treaty obligations. In an effort to establish a requirement of actual and freely given consent as the basis of international obligations, these new states have attempted to translate the principle of sovereign equality into specific rules of international law and to apply these rules to the traditional notions of consent. It is these rules, derived from the legal fiction of absolute sovereign equality, that are being translated into rules of treaty law governing the formulation and interpretation of treaties. The technique of inferring or implying consent as a basis of obligation in conventional international law is specifically rejected.
Stuart S. Malawer,
A New Concept of Consent and World Public Order,
4 Vanderbilt Law Review
Available at: https://scholarship.law.vanderbilt.edu/vjtl/vol4/iss1/1