In the case of Neely v. Henkel, 1900, the U.S. Supreme Court was asked to determine whether a U.S. citizen could be extradited from Cuba (then under temporary military governance by the United States) without formal proceedings or treaty provisions in place between the two countries. Charles F.W. Neely had been charged with embezzlement and fraud while serving as a postal official in Cuba and fled to avoid prosecution before being arrested and ordered for extradition back to Cuba by a U.S military governor there. Neely's lawyers argued that his rights were violated because he was not given due process according to American law nor protected by any existing extradition treaties between America and Cuba at that time. The court ruled against Neely, stating that since he committed crimes on Cuban soil when it was under temporary American control following Spanish-American War, he could indeed be extradited back there for trial even without an established treaty or formal legal proceedings taking place first within America itself.

In the dissenting opinion for Neely v. Henkel, Justice John Marshall Harlan argued that the majority's decision to allow extradition without a formal treaty in place was unconstitutional. He contended that this ruling violated the principle of federalism by allowing federal authorities to override state laws and protections without explicit authorization from Congress or an international agreement ratified by the Senate. Furthermore, he expressed concern about potential abuses of power and violations of individual rights if extraditions could be conducted based on mere executive agreements rather than legally binding treaties. In his view, such a practice would undermine due process guarantees and other constitutional safeguards against arbitrary government action.