North Korea and Customary International Law

North Korea and Customary International Law

By Sanya Shahrasbi, Staff Contributor 

For a decade now, North Korea has been testing nuclear weapons underground.[1]

In 2006, the country’s first nuclear test leaked the radioactive element xenon-133 over 4,500 miles away in Yellowknife, Canada.[2] Although there have been no large-scale catastrophic radioactive leaks thus far, scientists predict that continued earthquakes subsequent to the tests will increase the risk of exposing radioactive waste to underground water, poisoning flora and fauna for years.[3] The potential environmental ramifications from these kinds of leaks can be catastrophic and far reaching, eventually impacting humans as consumers of those plants and animals not just in North Korea, but in all East Asia.[4] In addition to underground testing, North Koreans now look to the sky, where the radiation is less contained, as their next testing ground to prove their nuclear capability to the world.[5] But can they? Or do they owe some environmental responsibility to their neighbors and the international community?

As we examine the laws surrounding nuclear testing, there is more support that allows North Korea to continue this practice. International environmental law can be created both through treaties, but also through non-binding instruments such as customary international law.[6] Customary international law is the widespread general practice of states and a sense of international legal obligation, or opinio juris.[7]

Nuclear testing can be analyzed from both of these sources of international law.

There are two nuclear testing treaties that emerged out of policy concerns for the well- being of the earth and its inhabitants: The 1963 Treaty Banning Nuclear Weapons Tests in Atmosphere, Outer Space, and Underwater (Partial Test Ban Treaty), which banned atmosphere, and underwater nuclear testing; and the 1996 Comprehensive Test Ban Treaty (CTBT), which banned all nuclear testing, including those underground.[8]

Because most North Korean tests have been underground, we look to the CTBT. Although the CTBT has not been formally ratified by either the U.S. or North Korea, the small group of countries that have nuclear weapons show some state practice to support the proposition that a comprehensive ban on all nuclear testing has become general state practice. The last underground test was conducted by India and Pakistan in 1998; these are the only two countries, apart from North Korea, that have broken the terms set out in the 1996 comprehensive nuclear testing ban.[9] In addition, the last above atmospheric nuclear test was conducted in 1980 by China.[10] Thus, it can be argued that within the international community the countries that have the capability to test nuclear weapons have generally refrained from doing so—particularly above ground.

Yet this analysis runs into trouble when we look to see whether the countries refrain from testing as a source of legal obligation or specialized behavior. So far, no state has publically said that their lack of testing stems from a source of legal obligation. Theses treaties have also not been ratified, further supporting the idea that there is no legal obligation. It seems most states prefer to keep nuclear testing in self-interest, to always have that option.

Thus, the international treaties and customary international law are not strong arguments to protect the environment against North Korean nuclear testing. It seems that even though the international community is concerned about the effects of these tests, they are not willing to state that there is a legal obligation not to test them. Because of this, we cannot efficiently enforce bans on nuclear testing in other countries, and trying to stop North Korea presents a challenging hurdle for the international community.


[1] What happens with an underground nuclear test?, CNN (Feb. 19, 2013, 1:40pm),

[2] Id.; Jonathan Medalia, North Korea’s 2009 Nuclear Test: Containment, Monitoring, Implications 12 (Diane Publishing Co., 2010).

[3] Neil Connor, Radiation leak at North Korean Nuclear site ‘inevitable’, says Chinese expert, Telegraph (Sep. 5, 2017, 2:50 pm),

[4] Id.

[5] David E. Singer and William J. Broad, Prospect of Atmospheric Nuclear Test by North Korea Raises Specter of Danger, N.Y. Times (Sept. 22, 2017),

[6] Lori Fisler Damrosch & Sean D. Murphy, International Law  Cases and Materials 1467-70 (West Publishing Co., 6th ed. 2014)

[7]  Id. at 60-61 (explaining that Article 38(1)(b) of the Statute of the International Court of Justice refers to “international custom, as evidence of a general practice accepted as law”).

[8] What happens with an underground nuclear test?, CNN (Feb. 19, 2013, 1:40pm),

[9] Id.

[10] Id.

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