The ongoing UNFCCC Negotiations at COP 23 in Bonn, Germany shows increasing evidence of Trump’s intention to withdraw from the historic Paris Agreement signed by the US under President Obama’s leadership in 2015. The Paris Agreement is one of the fastest multilateral treaties in international law to have been signed and ratified by almost all nations.

The recent addition of war-torn sovereign state Syria brings the total number of signatories to the Agreement to 196 out of a total of 197 states. Till date 170 signatories have also ratified their international commitments under the Paris Agreement by incorporating it within their domestic legal framework.

According to Article 28 of the Agreement, the intention expressed by the United States to exit can only come into effect from November 4, 2020. However, US President Trump has already expressed US’s intentions to make a de facto exit from its international commitments made under the Agreement by repealing various climate change mitigation and climactic adaptation schemes implemented under Obama’s regime such as the Clean Power Plan.

Being the richest economy and one of the top global polluters, the US’ backtracking on its international environmental commitments could have disastrous effects on the international implementation of the Paris Agreement and global climate mitigation and adaptation measures. Experts across the globe have voiced concerns about the international impact of US’ withdrawal from the Agreement by specifically highlighting the fragile legal position of the non-binding international commitments made by other countries.

However, from a purely international law analysis it appears that US’ expected withdrawal from the Agreement may not be as disastrous as many imagine and may not actually dilute the strength or validity of international obligations and commitments made under the Agreement.

Does the Paris Agreement reflect Customary International Law?

International law is derived from certain finite and more or less clearly defined sources including treaty law, customary international law, general principles of international law and the writings of publicists. Among these, treaty law is the most modern source of international law as it was brought into existence due to the establishment of international organizations such as the United Nations, World Trade Organization, etc.

The Vienna Convention on Law of Treaties (VCLT), 1969 codifies the law applicable to international treaties. It defines a treaty as “an international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation.” The VCLT defines customary law as “evidence of a general practice accepted as law.”

Although treaty law has acquired the distinction of being the most formal source of international law, this does not mean that it completely predominates the effect of other sources. For instance, when treaties reflect customary international law, non-signatories are bound not by the treaty provisions but rather by the customary international law or customary practices which are codified in the provisions of the treaty. Non-parties may also come to accept that provisions in a particular treaty can generate customary law, depending on the nature of the agreement, the number of parties to the treaty and other relevant factors. The idea of this crystallization effect comes from the belief that treaties and customary international law represent not so much independent sources, as they do the existence of a given norm at a given point in time. When a treaty regime is accepted by a supernumerary, the norm that the treaty regime codifies, transcends pure treaty law and gains recognition as a rule of customary international law.

Customary international law does not require ratification or formal acceptance by States in order to become binding. This is especially true for customary laws concerning human rights, environmental protection and other similar issues which are fundamentally of universal importance.

Over the years, several customary laws of such nature have been formally codified into the form of various treaties such as the Universal Declaration of Human Rights, Kyoto Protocol, Convention on Biological Diversity, Convention on International Trade in Endangered Species of Wild Fauna and Flora, etc. However, codification into treaties does not remove the customary nature of such laws which continue to have their independent strength even after codification into treaties.

In the context of the Paris Agreement, the overwhelming support received from almost all countries and the commitments made over the course of the last three years indicate a strong prevalence of custom. The fact that almost all nations regardless of their level of economic development or political stability or other internal struggles have come together to take action against climate change shows the rapid development of a customary practice. Hence, the fundamental provisions under the Paris Agreement can be said to have acquired the status of customary international law. Therefore, even non-signatory countries are under a legal obligation to abide by these customary principles, regardless of the obligations stipulated under the Paris Agreement. According to Ann Carlson, Professor of Environmental Law at UCLA, “if Trump doesn’t withdraw the U.S. from the 1992 UNFCCC, we remain a party to it and would still have to meet our obligations under the treaty, including providing data about our greenhouse gas emissions”.

Luke Kemp of the Australian National University's Fenner School of Environment and Society opines that “withdrawal is unlikely to change US emissions since the greenhouse gas emissions of the US are divorced from Paris Agreement obligations”.

In conclusion, although Trump’s steadfast opposition to consequently the US’ withdrawal from the Agreement, could have short term impact on the fight against global warming; in the long run, the US’ status as a signatory or non-signatory will be come largely redundant as it will be obligated to conform to customary international law principles emerging as the global norm from the Paris Agreement.

Srinivas Raman

B.A.,LL.B. (Business Law Hons.)

National Law University, Jodhpur