This article has been written by Ms. Diprava Ghosh a second year BA.LL.B student of Adamas University.

ABSTRACT:

One area of international law that deals with the concept of custom is known as customary international law. The International Court of Justice, jurists, the United Nations, and its member states view custom as one of the main sources of international law, alongside basic principles of law and treaties. One of the main tenets of international law is customary international law. Over the course of the previous 250 years or more, this dynamic legal process has developed close ties to our own domestic legal systems. Customary international law has also historically been accepted as a component of the “law of nations,” a term that our courts have alternately employed with the term “international law” since the formation of the United States. Unlike responsibilities derived from formal written conventions and treaties, customary international law refers to obligations deriving from accepted international practices. As the global system encounters novel and intricate obstacles, the development of CIL highlights its adaptability and durability. Maintaining a rules-based international order that tackles the complexity of the modern world and encourages collaboration among nations based on common values and practices depends on its continued evolution.

KEYWORDS: International Law, Customary Law, Evolution, Definition, International Humanitarian law.

 INTRODUCTION

: Along with treaties, customary international law (CIL) is a major source of international law. It is shaped by state practices that are widespread and consistent, as well as by the perception that the law mandates these practices (opinio juris). Customary international law basically develops when governments follow a pattern of conduct because they believe it to be required by international law. While perspectives on the specific norms that comprise customary international law vary, many states acknowledge its existence in principle. If two conditions are satisfied, a rule becomes customary internationally: (1) A state practice that “appears to be sufficiently widespread, representative as well as consistent” indicates that the norm in issue has been utilized and relied upon by a considerable number of states, and that a large number of states have not rejected the notion, (2) States were driven by the conviction that, under customary international law, they were legally bound to recognize the legitimacy of the contested regime(opinio juris). The following sources were listed by the International Law Commission in 1950 as proof of customary international law: treaties, rulings from domestic and international courts, national laws, legal advisor opinions, diplomatic correspondence, and international organization practices. Conclusions on Identification of Customary International Law with Commentaries were adopted by the Commission in 2018. The Conclusions were well received by the UN General Assembly, which also recommended that they be distributed as far as possible.

Key Elements: 

• General practice: Over time, states adopt a regular behavioural pattern. This may entail doing something, not doing something, or doing both at once.
• Opinio juris: According to state opinion, their activities are mandated by law (opinio juris sive necessitatis). It’s not only a matter of habit; it’s also a conviction that the action is required under international law.

What is Customary International Law?

International law derives from both treaty law and customary international law. States legally adopt some standards through written agreements called treaties, as the four Geneva agreements of 1949. Only States that have indicated their agreement to be bound by a treaty are obligated to do so, often by ratification. Contrarily, “a general practice accepted as law” is the source of customary international law. Official narratives of military operations, as well as a range of other official publications, such as military manuals, national laws, and case law, all reflect this approach. “Opinio juris” refers to the necessity that this practice be “accepted as law”. This feature distinguishes, for example, between actions taken as a matter of policy and actions mandated by law.

Why is International Customary Law Enforceable?

States acknowledge the obligatory nature of customary international law and treaties as sources of international law. For instance, the International Court of Justice’s Statute lays this forth. The implementation of customary international law by national and international courts and tribunals is one example of its binding character.

By Customary International Humanitarian law, Who is Bound?

Since the general goal of international law is to govern interactions between States, States are obliged to abide by it. This also applies to international humanitarian law, which governs armed conflicts between States and can be found in treaties or customs. Nonetheless, one unique aspect of international humanitarian law is that some of its provisions govern violent confrontations between armed opposition groups or between States. Whether a State or an armed resistance organization, all sides are subject to the regulations governing such confrontations. Numerous customary international humanitarian law norms that apply to non-international armed conflicts bind both States and armed opposition organizations, according to a review of State practice.

Evolution of Customary International Law: 

1. Traditional Methods: The customs of historical governments and civilizations serve as the foundation for customary international law. There were many different kinds of norms guiding interactions between entities, most of which were derived from unwritten rules and customs.
2. Renaissance and Medieval Times: In the Middle Ages, natural law and the Church served as the foundation for the development of customary law. During the Renaissance, maritime conventions and trading activities began to impact customary standards.
3. Westphalian Peace (1648): An important turning point in the history of international relations was the Peace of Westphalia, which established the notions of non-intervention and state sovereignty. This impacted the evolution of state practice and established the groundwork for the Westphalian system.
4. Maritime Law and the Spread of Colonialism: Customary standards in marine law emerged in the 17th and 18th centuries. Conventions pertaining to trade, territorial seas, and navigation established the foundation for international law. Customary standards evolved as a result of European colonial expansion and contact with indigenous populations.
5. 19th Century: Certain customs, especially those pertaining to diplomatic relations and the rules of war, were codified throughout the 19th century. Customary rules during times of armed conflict are becoming increasingly recognized, as seen by the creation of the Geneva Conventions and the Red Cross.
6. After World War I: International law was attempted to be codified through treaties and organizations such as the League of Nations in the aftermath of World War I. Customary rules were, nonetheless, still greatly influenced by governmental practice.
7. After World War II:

• Nuremberg Trials (1945–1946): The Nuremberg Trials impacted the formation of customary international law by establishing concepts of individual criminal culpability for war crimes.
• Universal Declaration of Human Rights (1948): The 1948 Universal Declaration of Human Rights is seen as a reflection of customary standards and has contributed to the development of human rights legislation, although not being a legally enforceable agreement.

1. Sustainable Development and Environmental Law: Environmental law had a substantial advancement with the Stockholm Conference on the Human Environment in 1972. Customary rules evolved as a result of state initiatives pertaining to sustainable development and environmental preservation.
2. Duty to Preserve: The idea of “Responsibility to Protect,” which highlights the obligation of the international community to step in when mass crimes occur, is a post-Cold War culture that is beginning to take shape.
3. Cybersecurity and Contemporary Issues: State activities in cyber operations have contributed to the development of customary international law in this area with the growth of cyberspace. The international community is having difficulty creating standards to deal with cybersecurity problems.
4. Modern Difficulties: Emergencies relating to global health, like the COVID-19 pandemic, and initiatives to mitigate climate change are impacting the formation of customary norms for public health, environmental protection, and international collaboration.
5. The post-Cold War era: Customary international law faced new opportunities and problems with the end of the Cold War. The establishment of international criminal tribunals, governmental accountability, and humanitarian initiatives gained prominence.
6. Climate Change: Conventional norms pertaining to environmental preservation, sustainable development, and governmental obligations are formed in part via efforts to combat climate change.

CONCLUSION: A dynamic and ever-evolving area of international law, customary law is influenced by notable previous state practices, current issues, and historical events. Customary international law changes to solve new problems and represent the common goals and responsibilities of the international community as state conduct and ideologies continue to change. Throughout its history, CIL has evolved to reflect shifts in the field of international relations, from its early roots in antiquated customs to the formalization of standards during the Peace of Westphalia. Its growth was aided by the United Nations’ formation and the codification efforts that followed World Wars I and II. The Nuremberg Trials pushed the bounds of conventional conventions by introducing the concepts of individual criminal culpability. Human rights, environmental preservation, and humanitarian intervention are some of the post-Cold War problems that have influenced the development of CIL. The rise of notions such as Responsibility to Protect and the growing significance of cybersecurity attest to its continuous adjustment to modern-day obstacles. Responses to situations involving global health and initiatives to tackle climate change demonstrate the continued relevance of CIL in solving global concerns. Its tenets, derived from the common customs and ideologies of nations, continue to direct interactions between states, guaranteeing a structure that represents the duties and commitments of the international community as a whole. 

Reference:

1. This article is published in 

https://en.wikipedia.org/wiki/Customary_international_law

1. This article is published in 

https://www.icrc.org/en/war-and-law/treaties-customary-law/customary-law

1. This article is written by 

Jordan J. Paust 

University of Houston

Customary International Law: Its Nature, Sources and Status as Law of the United States, 

12 MICH. J. INT’L L. 59 (1990). 

Available at: https://repository.law.umich.edu/mjil/vol12/iss1/2

1. This article is published in https://www.law.cornell.edu/wex/customary_international_law#:~:text=Customary%20international%20law%20refers%20to,formal%20written%20conventions%20and%20treaties.