Customary International Law: Herding Cats in Zero Gravity

On the soccer field, it is not always entirely clear what behaviors a good sportsman should take, no matter how earnestly one pursues such laudable behavior. In some instances, rules guide players to sportsman-like behaviors. For example, it is considered unsportsman-like for the offense to cherry pick or to grossly outnumber the defense; therefore soccer’s offside rule was created. But this rule codifies only a narrow aspect of the custom of good sportsmanship in the beautiful game, leaving other aspects of sportsmanship defined by player custom.

In much the same way the offside rule was eventually created to explicitly direct soccer players toward fair behavior on the soccer field, international treaties like the Geneva Conventions are often created to delineate proper behavior from improper/war-like/criminal behavior throughout the world. Despite customs of humane treatment of others during war and traditions of good sportsmanship on the soccer field, neither the soccer community nor the international community have been able to put in writing and agree to a complete set of behaviors which proscribe the proper humane or sportsman-like action to take in every situation. In many areas, unwritten international custom defines the legality of an action. Lack of consensus or consistency of behavior can make it difficult to properly define customary international law.

When it comes to emerging industries like extraterrestrial resource mining, customary international law can seem like attempting to herd cats in zero gravity. Pinning down what is “fair” and “customary” in areas where no man has gone before can seem daunting but it also presents the unique opportunity to shape international custom by establishing them.

Where does international law come from?

There are many sources of law. Historic custom; international treaty; local ordinance; a nation’s constitution, the philosophical, political, and economic arguments made to pass a constitution or a law; even modern interpretations of centuries old legal language. The tapestry of modern law has been woven by an ever changing committee of weavers some of whom contributed yards of work while others merely pointed out the one thread in a corner missed a stitch. Despite this cacophony of legal voices and sources, the law can be divided into two categories: mandatory law and persuasive law. In simple terms, mandatory laws are laws binding. These laws must be followed in a specific situation. Persuasive laws, on the other hand, do not have to be followed but can influence binding law.

International law comes from two sources: international agreements and custom. International agreements bind not only the behavior of nations but also of people through the application of international treaties to a nation’s citizenry. In the United States, the Constitution declares treaties “the supreme Law of the Land,” applying provisions of the Outer Space Treaty to government actions and private citizens alike. Customary international law is often persuasive, but can be binding, depending on the situation and how well established the custom is.

What is customary international law?

In general, customary international law consists of laws which bind all the nations of the world, even where a nation has not actually signed a treaty or enacted a local law to that effect.

The United Nations and its member states, as well as the International Court of Justice, consider some international custom to be a binding source of international law. Many extremely important areas of law have historically been defined by the traditional actions taken and statements made by countries through history. For example, both the laws of war (e.g. the meaning of a declaration of war) and the law of the sea (e.g. salvage rights, acts of piracy) were long defined by customary international law. In the 20^th century, many aspects of both the laws of war and the law of the sea were codified by international agreements like the Geneva and Hague Conventions for war and UNCLOS for the sea. Some aspects of the laws of the sea and of war are still governed by custom. The launch of Sputnik in 1957 established the international custom “of free passage in space even when that passage transits over the territory” of another nation.

International custom is not necessarily defined by actions taken by countries. Provisions of international treaties may become part of customary international law and bind countries which have never become a party to that treaty. An international dispute between Germany, Denmark, and the Netherlands explored criteria which can indicate that a treaty’s provisions have become customary international law, binding on other nations regardless of their agreement to the treaty itself. These criteria include the length of time the treaty has been in force, whether non-party states objected to the provisions alleged to have become customary, and the number of countries that have signed the treaty. In other words, both a long established treaty and a treaty signed by a significant number of countries may contain provisions which can be considered customary international law which binds all the nations of the world.

The precise boundaries of customary international space law are difficult to pin down. Scholars like Francis Lyall and Paul Larsen believe that at least some provisions of the 1967 Outer Space Treaty, which has been signed or ratified by more than half of the world’s nations, has become customary international law. Others, like Michael Listner, argue that provisions of the less popular but long standing 1979 Moon Treaty may have become customary. Specifically, arguments have been made that provisions prohibiting private ownership of asteroid and moon resources may be customary international law, potentially complicating profitable extraterrestrial mining operations. On the other hand, law is rarely predictive and is often shaped by the very pioneers that open up new physical, mental, or technological frontiers. Just as the USSR’s launch of the first artificial satellite into orbit established the customary norm that overflights of a sovereign nation are legal if they’re made by orbiting satellites in space, future space pioneers will likely have the opportunity to influence or establish international custom through the actions they take.

Happy creating!