What is Customary International Law?

In this article we are going to get legal-beagle and try to clear up just exactly what customary international law is – and is not. The truth is, in the world of law there are a number of ongoing discussions as to what can and cannot fall under this legal mumbo jumbo.

The simplest example that the average person is familiar with is “diplomatic immunity.” More than a few movies are based on this idea where an ambassador (or family member) from another country commits a crime and is allowed to remain free of any legal ramifications for their actions. Of recent vintage are the Russians found to have been involved in meddling with the 2016 presidential election. Rather than be imprisoned under American law, they were simply expelled from the United States and not allowed to return.

More formally, customary international law are rules of law that individual nations can expect to hold true based on the consistent conduct of other nations. For example, it is generally understood no matter what country you are in that murder is wrong and punishable in a court of law. Other than formal diplomats, such as ambassadors, murderers will be arrested and held accountable regardless of what country they are in.

Legally, there are three basic guidelines for determining whether an action is considered to be applied as a customary international law. The first is what is known as a State practice. Basically this is something that is done in a country or culture repeatedly over a period of time. But the sticking point is that it has to be an international act. So for example, Americans have freedom of speech and so a foreign visitor can be expected to have the same freedom of speech while they are visiting the country. In contrast, the same right to freedom of speech is not recognized in Iran, so speaking against the State in Iran can land you into legal trouble because freedom of speech is not a State practice there.

The second requirement is a bit difficult to understand. In the law it is known as opinio juris. To qualify as customary international law there must be a sense of obligation attached to a specific act. An example here might be being a member of the International Red Cross and practicing medicine while in another country. It is generally considered to be a moral obligation for a professional doctor to help someone who requires medical attention. It is rare when you can find an example where such actions do not fall under the protection of customary international law.

Finally, there is the concept of a simple majority rule. Technically, the word “significant” applies here when defining a majority, making the application of this concept somewhat murky. It also applies to the idea that a “significant” number of countries do not reject the specific rule of law. While murder is almost universally accepted as being a violation of the law, an individual’s complete freedom of speech has been rejected by a “significant” number of countries and fails the third test.

So how do you know what is and isn’t customary international law? Fortunately, there are some guidelines that have been established back in 1950 by the International Law Commission. The following are legal evidences that can be reasonably expected to support an action that falls under the concept of customary international law.

  • Treaties – these don’t have to be the result of an act of war but can be simple agreements between nations
  • Decisions of national courts and international tribunals – the legal difference between a court and a tribunal isn’t significant here; simply recognize that if there is a legal national or international precedent you likely are OK
  • National legislation – this is different than the decision of a national court as it involves a different governmental institution
  • Diplomatic correspondence – simply put, what you write between diplomats or similarly appointed authorities is reasonably safe
  • Practices of international organizations – such as the International Red Cross

That about covers the concepts and requirements for an act to fall under the legal concept of customary international law. Honestly, this is a subject more suitable for law students and people who actually practice international law. But at the same time it is important for you to know the basics so when traveling you can have some idea as to what actions are not permissible in other countries and not protected under the law, such as defiling religious temples, taking a selfie next to a national treasure, or speaking treason against the leader of a foreign country. Your individual rights are usually not transferable from one country to another.

Add Comment

What Exactly is Labor Law?
10 Things You Didn’t Know about Tort Law
What Does a Civil Litigation Lawyer Do?
What is Customary International Law?
10 Things You Didn’t Know About Georgetown Law School
10 Things You Didn’t Know about Harvard Law School