This paper is a case study concerning the International Court of Justice case Nicaragua v. United States, detailing what precedents and clarifications the case established for the ever-dynamic field of international law. In 1984, after the United States financially supported military and paramilitary groups in Nicaragua to overthrow the Nicaraguan FSLN government (which was installed by the United States in the early 1970s), the Nicaraguan government filed an appeal with the International Court of Justice. Overall, Nicaragua v. United States advanced the implementation of international law by effectively clarifying the implications and accountability of international law and establishing a universal definition of collective self-defense.