What Is International Law?

The laws that govern the dealings between nations

By Super Lawyers staff | Reviewed by Canaan Suitt, J.D. | Last updated on February 3, 2023

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International law is a broad and complex area of practice. It consists of the rules, regulations, statutes, and treaties governing the dealings between nations, including individuals, businesses, and organizations. Many different issues are implicated in international law, including

  • Foreign relations
  • Commercial transactions
  • Environmental concerns
  • Human rights
  • Criminal matters, including cases before the International Criminal Court (ICC)
  • International humanitarian law (or law of war) limiting armed conflict
  • Military and national security matters, including imposition of sanctions and authorization of the use of force to protect the international community

The following information is meant to provide a brief overview of international law. If you have any specific questions or concerns about international law, you should consult with an experienced attorney.

International Law – What You Need to Know

  • International law can be broadly divided into two categories: public and private.
  • Public international law refers to the direct dealings between nations. It governs how nation-states work with each other and how nation-states treat citizens of other countries.
  • Private international law regulates the dealings between individuals and businesses residing in different jurisdictions.
  • International law also covers a wide range of different specialty fields, which are covered in detail below.

An Overview of International Law

The rules of international law can be divided up into two relatively broad categories:

  • Public International Law: Public international law refers to the direct dealings between nations. It governs how nation-states work with each other and how nation-states treat citizens of other countries. For example, a free trade agreement between the United States and Colombia falls under public international law. Countries engaged in treaty negotiations owe each other certain customary obligations of good faith and fair dealing under international regulations. A dispute in international relations could go before an international body, such as the International Court of Justice (ICJ).
  • Private International Law: Private international law regulates the dealings between individuals and businesses who reside in different jurisdictions. As the world economy becomes more globalized, many companies need guidance on international commercial matters. For example, a multinational commercial agreement between a company based in the United States and a supplier based in China would fall under private international law.

The Domains of International Law

The United Nations (UN) defines international law as the “legal responsibilities of States” in their interactions. In the UN, the term “states’ refers member states or nations that are enrolled in the organization. It would be a mistake to view international law as “one thing.” Like domestic law, international law covers a wide range of different specialty fields. The main practice areas that fall under international law include:

  • International Commercial Law: Most lawyers who practice international law deal primarily with commercial matters. We live in a globalized economy filled with international organizations all with their own goals and objectives. The United Nations Conference on Trade and Development (UNCTAD) reports that international trade hit a record high of $28.5 trillion in 2021. International commercial transactions can be more complicated than domestic transactions. Lawyers help parties navigate various issues, including multinational trade agreements, customs, international business regulation, international commercial arbitration and business disputes, and global intellectual property (IP) issues. An international commercial law attorney can help you navigate complex cross-border transactions.
  • International Criminal Law: Criminal law is still essentially a domestic matter. However, international criminal law has become a more critical issue in an increasingly globalized world. International criminal laws seek to address alleged illicit conduct that crosses national boundaries. It encompasses many different issues—from extradition treaties to war crimes tribunals in international courts.
  • International Security Law: Military and national security law are among the most critical aspects of public international law. International law professionals deal with treaty negotiations, diplomacy, military cooperation, prisoners of war, security councils, and related issues within this field. Within diplomatic law, international lawyers must navigate the rights and obligations that states and their representatives have to each other.
  • International Environmental Law: The environment affects everyone on the planet. The environmental practices of one country could have significant implications not just for its immediate neighbors but for everyone else on the planet. International environmental law is a practice field focused on regulating conduct by states (and corporations) regarding the environment. International environmental law affects nation-states and private actors. A nation-state may be determining whether or not to enter a specific international agreement, such as the Paris Climate Accord. A multinational company may need to set up a process that complies with certain global environment regulations while engaged in a cross-border developmental project.
  • International Human Rights Law: The sub-field of international human rights was developed following the end of World War II. The formation of the United Nations provides international legitimacy and authority to protect human rights. Indeed, the UN Charter specifically mentions human rights. The UN defines human rights as “inalienable rights of all members of the human family.” International human rights lawyers provide guidance to governments and private parties.

Understanding the Sources of International Law

One of the core challenges of international law is legitimacy. While legitimacy is an issue in any legal system, the source and enforceability of applicable law is generally a less challenging issue in domestic cases. However, source and enforceability can be an area of dispute in a multinational legal matter. International law arises from two key areas: customary law and conventional law.

Customary international law is the “law” that arises from generally established practices instead of a formal agreement. International customs matter, and international legal principles matter. They could be viewed as binding in certain circumstances. Customary international law was codified in the Vienna Convention on the Law of Treaties, effectively the treaty of treaties.

In contrast, conventional international law arises from formalized international conventions, such as treaties. Both customary international law and conventional international law are essential and could impact a legal matter.

Determining the source(s) of international law in any given case can be complicated—especially if you are dealing with a somewhat novel issue. There may be applicable international customs, general principles of law, or formal treaties that could all play a role in the case.

Understanding the Role of International Law in the United States

The United States has a general policy toward respecting the laws of other nations unless there is a specific statute or treaty that holds to the country. In the international domain, U.S. citizens and American-based companies can be subject to international customs and international treaties. At the same time, the United States federal government has a clear policy dictating that international law does not and will not restrict the U.S. from making rules and regulations to govern its territory.

Common Questions About International Law

One of the first steps to navigating an international law case is setting up a consultation with an experienced lawyer. An international law attorney will be able to review the matter and help you determine the best course of action. To get the most out of a meeting with a lawyer, you need to ask the right questions. Here are some of the most common questions for international law attorneys:

  1. What sources of law apply to my international law case?
  2. Is there a statute of limitations that I need to be aware of?
  3. Are there any related domestic law matters that I should know about?
  4. How can an international law attorney help me address my legal obligations?
  5. Do I have to appear before an international tribunal?
  6. Are there any options to resolve the matter outside of litigation, such as arbitration?
  7. What steps do I need to take to protect my rights and interests?

Finding the Right Attorney for Your Needs

It is essential to approach the right type of attorney—someone who can help you through your entire case. To do so, you can visit the Super Lawyers directory and use the search box to find a lawyer based on your legal issue or location.

To help you get started, you may want to consider looking for a lawyer who practices international law.

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