Institutionalism is one of the approaches that emerged from international relations, which is the product of the debate with realists, and at the same time, a rejection of the functionalists . This theory, while assuming the findings of realists regarding the anarchy prevailing in international relations and the self-interest of states, seeks to prove the possibility of cooperation between actors, especially states, and analyzes the issue of how institutions are formed and how international law is observed through them. Recent approaches based on institutionalism, which pursue the consolidation of this theory, despite accepting the traditional sources and subjects of international law and acknowledging their preservation, pay very special attention to soft law as the desired law in line with the institutionalization of international law. The special importance of institutionalism for soft law, as it considers international law as both a legal and political process, will be able to change the sources and subjects of international law and even the basis for the obligation of international law; so that it may be possible to speak of non-binding but institutionalized and largely enforceable laws on this basis. This is the point of importance of this theory for international law that can affect the international legal order, and therefore institutionalism should be considered beyond the mere analysis of the possibility of cooperation in international relations; because the history of international law is full of institutions. The Financial Action Task Force is among the institutions whose study can confirm the above finding.