International Law: What Makes Nations Get Along?

By Rebecca Schembri, Harvard University Extension School, April 7, 2021

International law is a system set up by nations, or states, to engender civilized predictability in relations between each other. Since states prosper in times of peace, and benefit from working together in commerce and intellectual growth, it is to a nation’s advantage to remain amicable with the rest of the world. Although international agreements do not inherently supersede a state’s national constitution, they are considered binding—only to be violated when the core values of a nation are questioned. States take international law seriously, writing its defense into their constitutions and honoring tradition in the absence of formal treaties. However, depending on a state’s attitude, such laws are not taken as supreme, and can be overridden when necessary.

Photo Caption: The United Nations aims to maintain international peace and security

The importance of international law may be seen in state constitutions worldwide. Illustrating such gravity, the constitution of the Italian Republic states that the “…Italian legal system conforms to the generally recognised principles of international law….” Likewise, South Africa’s constitution proclaims that the “… Republic is bound by international agreements.” These countries are not alone in forming accords with other nations, in fact, most states make room for it in their founding documents. Article VI of the Constitution of the United States of America decrees that: “all Treaties made, or which shall be made, under the Authority of the United States, shall be the supreme Law of the Land; and the Judges in every State shall be bound thereby, any Thing in the Constitution or Laws of any State to the Contrary notwithstanding.” Under this document, treaties with other countries are protected and upheld.

rebecca from reno
Photo Caption: At the United Nations, states agree to the terms of International Law

Customary law, or the longevity of practice, can also be binding, as in the case of violated rights of Cuban fisherman, The Paquete Habana. Here, courtesies that had been observed for centuries were not easily undone when the U.S. Supreme Court ruled in favor of the boat owners, obliging spoilers to pay damages on goods they had confiscated. This accountability to custom was explained by the court: “…where there is no treaty and no controlling executive or legislative act or judicial decision, resort must be had to the customs and usages of civilized nations, and, as evidence of these, to the works of jurists and commentators.” This urgency of international customary law is considered a vital part of organized rule.  

rebecca from reno
Photo Caption: Modern Space Law requires international agreement

Depending on their political beliefs, however, states adhere to international law differently. This can be catalogued into two sections: monist or dualist, and, according to scholar David J. Bederman’s writings, hinges on “whether a domestic constitution or statute can ‘[override]’ a customary international law or treaty obligation as a matter of domestic law.” This means that if states adopt international law without question, it becomes their law, whereas a state that first honors its own laws, then those of treaties it has signed, keeps a distinction between the two. Monist, and partially monist, states, such as the Netherlands, Germany, Italy, and Austria merge international law with their own and generally accept treaties and custom as firm. Although these states differ in their degree of acceptance, overall they uphold these laws as one with their internal legislation.

Photo Caption: International Law requires all astronauts to help each other, regardless of country origin

Dualist states, on the other hand, adhere to international agreements yet keep the obligations of such as secondary to their own. In the United States, for example, it is “well-established that neither a rule of customary international law nor a provision of a treaty can [repeal] a right granted under the Constitution.” Although international law is solemnly honored, the United States’ values, and those of other dualist nations, prevail in court over international interests. This was shown in the U.S. Supreme Court case Reid v. Covert, when an American woman’s constitutional rights were upheld even though she was charged for a crime in England. As situations like this arise, and states must choose between their international legal aspirations and their own centric beliefs, domestic courts will consider the nation’s laws before ruling. In South Africa, for example, Article 232 of its constitution states that “[c]ustomary international law is the law in the Republic unless it is inconsistent with the Constitution or Act of Parliament.” This failsafe to protect the needs of the country before the needs of diplomacy is also marked for international treaties the state has signed.

Photo Caption: Space exploration is an international effort

In sum, although a nation makes every intention to keep its word, it is bound by international law only as far as it chooses to be and may do so on an item-by-item rationale: “It is probably the case that almost all nations observe almost all principles of international law and almost all of their obligations almost all of the time,” wrote twentieth century scholar Louis Henkin. This strict keeping of laws except in dire situations is, in Bederman’s words, solidly fluid. “The best way of thinking about international law in this respect,” he writes, “is that it may well be “separate” from domestic legal systems but it is not “apart”. The laws of a nation include international law, and they are a branch of each state’s judicial system. As the U.S. Supreme Court observes, “international law is part of our law.” The hard decisions of honoring one’s internal obligations before the external are not taken lightly and carry a legacy of precedent. It is for state leaders to make these calls, and to reap the consequences of the histories they write.

Rebecca From Reno
Rebecca Schembri is a Social Science graduate student at Harvard University. Her concentration is in Space Diplomacy.
She is from Reno, Nevada, USA

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