Rising legalization in the international community has lead to greater use of international tribunals and soft law. This paper explores the intersection of these instruments. The decision of an international tribunal interprets binding legal obligations but is not itself legally binding except, in some instances, as between the parties. The broader, and often more important function of a tribunal's decision - its influence on state behavior beyond the particular case and its impact on perceptions regarding legal obligations - is best characterized as a form of soft law.
Despite its inability to bind states, a tribunal can influence state behavior by implicating a state's reputation for compliance with international law, by bolstering the reciprocity underlying an agreement, or by triggering retaliation. In this sense the rulings of a tribunal influences states through the same mechanisms as does binding international law. Because tribunal rulings are soft law, however, they avoid the need for unanimity among states, thereby making it easier for the legal system (including the non-binding aspects of that system) to adapt to changing circumstances and conditions.
By establishing a tribunal to interpret legal obligations in a way that gives rise to a soft law jurisprudence, therefore, states are able to expand the tribunal's influence beyond those states that submit to the tribunal's jurisdiction. In effect, all states subject to the underlying legal obligation come to be subject to the soft law impact of the tribunal, regardless of whether they have formally submitted to the tribunal's jurisdiction. In this way tribunals create what can be called an international common law able to evolve without formal agreement from states.
Timothy L. Meyer and Andrew T. Guzman,
International Common Law: The Soft Law of International Tribunals
Available at: https://digitalcommons.law.uga.edu/fac_artchop/757