Examples of international law include the UN Charter’s ban on the use of force, the Vienna Convention’s rules on diplomatic immunity, the Geneva Conventions governing armed conflict, the Universal Declaration of Human Rights and its two binding covenants, the Rome Statute that created the International Criminal Court, extradition treaties and mutual legal assistance agreements, the Paris Agreement and Montreal Protocol, World Trade Organization rules, the Law of the Sea Convention, and the Outer Space Treaty. Each one addresses a different problem that no single country can solve alone, and each works through a mix of state consent, treaty obligations, and institutions that interpret or enforce the rules.
The UN Charter as the Baseline
Almost every other example rests on two principles from the Charter of the United Nations. The organization is built on the sovereign equality of all member states, and every member must refrain from the threat or use of force against the territorial integrity or political independence of any state.1United Nations. Chapter I: Purposes and Principles (Articles 1-2) That baseline explains a defining feature of the field: countries are bound because they have agreed to be bound, not because a higher authority compels them.
Diplomatic Relations
The Vienna Convention on Diplomatic Relations, adopted in 1961, is the cornerstone of modern diplomatic law. Under Article 31, a diplomatic agent enjoys immunity from criminal prosecution in the host country, along with immunity from most civil and administrative proceedings. Narrow exceptions cover private real estate disputes and personal business activities unrelated to the diplomat’s official role.2United Nations. Vienna Convention on Diplomatic Relations A host country that wants to respond to serious misconduct cannot prosecute; it declares the diplomat persona non grata and sends them home.
Embassy premises are inviolable under Article 22. Local police and government agents cannot enter without permission from the head of mission. Article 24 extends inviolability to the mission’s archives and documents wherever they happen to be, and Article 27 protects official correspondence and prohibits opening or detaining the diplomatic bag. Diplomatic couriers themselves cannot be arrested or detained.2United Nations. Vienna Convention on Diplomatic Relations
Armed Conflict and Prohibited Weapons
The four Geneva Conventions of 1949 form the backbone of international humanitarian law. Each protects a specific category of people during armed conflict: wounded and sick soldiers on land, wounded and shipwrecked military personnel at sea, prisoners of war, and civilians.3International Committee of the Red Cross. The Geneva Conventions of 12 August 1949
Common Article 3 appears in all four conventions and sets a floor. Anyone not actively participating in hostilities, including soldiers who have surrendered or been wounded, must be treated humanely without distinction based on race, religion, sex, or similar criteria. Violence, torture, hostage-taking, and degrading treatment are banned, and the wounded and sick must be collected and cared for.4International Committee of the Red Cross. Geneva Convention (I) – Article 3: Conflicts Not of an International Character
The Third Convention treats a captured soldier not as a criminal but as an enemy combatant who can no longer fight and must be released when hostilities end. The Fourth Convention protects civilians under the control of a foreign power during conflict or occupation. Article 33 prohibits collective punishment: no one may be punished for an offense they did not personally commit, and measures of intimidation or terrorism are banned. Forcible deportation of protected persons from occupied territory is also prohibited.5International Committee of the Red Cross. Geneva Convention (IV) on Civilians, 1949 – Article 33
Separate treaties restrict specific weapons. The Chemical Weapons Convention obligates every state party never to develop, produce, stockpile, transfer, or use chemical weapons under any circumstances. Countries that possessed stockpiles when they joined were required to destroy them along with any production facilities, and the treaty even bans the use of riot control agents as a method of warfare.6Organisation for the Prohibition of Chemical Weapons. Article I – General Obligations Dangerous chemicals fall into three schedules based on weaponization potential and legitimate commercial uses; Schedule 1 chemicals face the tightest restrictions because they have been used as weapons and have few peaceful applications.7Organisation for the Prohibition of Chemical Weapons. Annex on Chemicals
Human Rights Standards
The Universal Declaration of Human Rights, adopted by the UN General Assembly in 1948, was the first document to set out fundamental human rights intended for universal protection. Its core guarantees include the right to life, liberty, and security (Article 3), the prohibition of slavery (Article 4), and the prohibition of torture or cruel, inhuman, or degrading treatment (Article 5).8United Nations. Universal Declaration of Human Rights The Declaration is not itself a binding treaty, but many of its provisions are now considered part of customary international law.
Two binding covenants translate the Declaration into legal obligations. The International Covenant on Civil and Political Rights protects freedoms such as the right to move freely within a country, the right to a fair hearing before an independent and impartial court, and protection from arbitrary interference with privacy, family, or correspondence. Each state party must adopt whatever laws are necessary to make these rights effective in practice.9Office of the United Nations High Commissioner for Human Rights. International Covenant on Civil and Political Rights The International Covenant on Economic, Social and Cultural Rights recognizes the right to work in fair conditions, the right to an adequate standard of living, and the obligation to progressively realize these rights using all available resources.10OHCHR. International Covenant on Economic, Social and Cultural Rights Together, the three instruments are often called the International Bill of Human Rights.
International Courts
The International Court of Justice
The International Court of Justice is the principal judicial organ of the United Nations, and only states can appear before it. The court settles disputes between countries in accordance with international law, but it can only hear a case when the states involved have consented to its jurisdiction.11International Court of Justice. Contentious Jurisdiction Consent can come through a special agreement between the disputing parties, a treaty clause designating the ICJ as the forum for disputes arising under that treaty, or a standing declaration accepting the court’s jurisdiction. Unlike a domestic court that can compel a citizen to appear, the ICJ depends on sovereign states agreeing to participate.
The International Criminal Court
The International Criminal Court, established by the Rome Statute, prosecutes individuals rather than states for the most serious crimes of international concern. Its jurisdiction covers four categories: genocide, crimes against humanity, war crimes, and the crime of aggression. Genocide means acts committed with the intent to destroy a national, ethnic, racial, or religious group. Crimes against humanity cover widespread or systematic attacks on civilian populations, including murder, torture, enslavement, and enforced disappearances.12International Criminal Court. Rome Statute of the International Criminal Court
The ICC operates on the principle of complementarity. It steps in only when national courts are unwilling or genuinely unable to prosecute these crimes themselves.13International Criminal Court. How the Court Works The court is a backstop, not a replacement for domestic justice systems.
Extradition and Cross-Border Legal Cooperation
When a crime crosses borders, countries use formal channels to share evidence and hand over suspects. Extradition treaties govern the transfer of individuals accused or convicted of crimes. A central requirement in most agreements is dual criminality: the alleged offense must qualify as a crime in both the requesting and the requested country.14United Nations Office on Drugs and Crime. Extradition A country generally will not hand over a person for conduct that is legal under its own laws. The modern trend focuses on the underlying behavior rather than whether both countries use the same legal label for the offense.
Mutual Legal Assistance Treaties handle a related task. They allow prosecutors and law enforcement agencies to formally request evidence, documents, records, and testimony from a foreign government for use in criminal investigations. Each country designates a central authority to send, receive, and carry out these requests; in the United States, that role falls to the Office of International Affairs within the Department of Justice.15U.S. Department of Justice. Mutual Legal Assistance Treaties of the United States Evidence obtained through an MLAT is intended to be admissible in the courts of the requesting country.
Environmental Treaties
The Paris Agreement
The Paris Agreement, adopted in 2015, is a legally binding climate treaty. Its central goal is to hold the increase in global average temperature to well below 2°C above pre-industrial levels, with efforts to limit it to 1.5°C.16UNFCCC. The Paris Agreement Instead of imposing uniform emissions targets, the agreement works through nationally determined contributions. Each country submits its own climate action plan describing how it will cut greenhouse gas emissions, and each successive plan must represent a progression beyond the prior one and reflect the country’s highest possible ambition.17UNFCCC. Nationally Determined Contributions (NDCs)
Article 6 creates a mechanism for countries to transfer carbon credits earned from emissions reductions. A company in one country can reduce emissions, earn credits, and sell them to a company in another country working toward its own climate targets. A share of the proceeds is directed toward adaptation funding in developing nations.18UNFCCC. Paris Agreement Crediting Mechanism
The Montreal Protocol
The Montreal Protocol, signed in 1987, targets chemicals that damage the ozone layer and is the first treaty in United Nations history to achieve universal ratification.19Environmental Protection Agency. International Actions – The Montreal Protocol on Substances that Deplete the Ozone Layer Signatories committed to phasing out ozone-depleting substances, including chlorofluorocarbons and halons, through defined reduction schedules and trade restrictions. The agreement also provides financial and technical assistance to help developing nations meet their obligations.20Ozone Secretariat. The Montreal Protocol on Substances that Deplete the Ozone Layer
International Trade
Global commerce runs on a set of interlocking agreements, most administered through the World Trade Organization. The foundational principle is most-favored-nation treatment, set out in Article I of the General Agreement on Tariffs and Trade: whenever a country lowers a trade barrier or opens a market, it must do so for the same goods from all WTO members. A related principle, national treatment, prevents countries from using domestic taxes or regulations to discriminate against imported goods once they have entered the market. Charging a customs duty at the border is permitted; taxing imported products at a higher rate than identical domestic ones is not.21World Trade Organization. Principles of the Trading System
The United Nations Convention on Contracts for the International Sale of Goods provides uniform rules for cross-border commercial transactions. It covers the formation of contracts and spells out what buyers and sellers owe each other. When one side breaches, the aggrieved party can demand performance, claim damages, or, in cases of fundamental breach, cancel the contract entirely.22United Nations Commission on International Trade Law. United Nations Convention on Contracts for the International Sale of Goods (Vienna, 1980) (CISG)
The Agreement on Trade-Related Aspects of Intellectual Property Rights sets minimum standards that every WTO member must meet for protecting copyrights, patents, trademarks, and industrial designs.23United States Patent and Trademark Office. Trade Policy TRIPS also requires enforcement mechanisms, including civil actions for infringement and criminal penalties for counterfeiting and piracy.24World Trade Organization. Overview of the TRIPS Agreement
International trade law also includes the power to restrict commerce. In the United States, the International Emergency Economic Powers Act authorizes the president to impose sanctions during declared national emergencies. Violating these sanctions carries civil penalties of up to $250,000 or twice the value of the prohibited transaction, whichever is greater. Willful violations can trigger criminal fines of up to $1,000,000 and up to 20 years in prison.25Office of the Law Revision Counsel. 50 USC 1705: Penalties
The Law of the Sea
The United Nations Convention on the Law of the Sea divides the world’s waters into zones with progressively decreasing levels of national control. Territorial waters extend up to 12 nautical miles from the coast, and within this belt the coastal state exercises full sovereignty over the water, the airspace above it, and the seabed below.26United Nations. United Nations Convention on the Law of the Sea
The contiguous zone extends up to 24 nautical miles. A state can enforce its customs, tax, immigration, and sanitary laws there to prevent or punish violations committed within its territory or territorial sea, but it does not have full sovereignty. The exclusive economic zone reaches up to 200 nautical miles. Within the EEZ, the coastal state has sovereign rights over natural resources, both living and non-living, and jurisdiction over activities such as energy production from wind and currents. Other nations retain the right to navigate and fly through, but they cannot exploit the resources without permission.27United Nations. Part V: Exclusive Economic Zone
Beyond all national zones lie the high seas. No state may claim sovereignty over any part of them. The high seas are open to all countries, coastal or landlocked, and include freedoms of navigation, overflight, fishing subject to conservation rules, and scientific research. These freedoms must be exercised with due regard for the interests of other states.28United Nations. United Nations Convention on the Law of the Sea – Part VII
Outer Space
The Outer Space Treaty of 1967 provides the basic legal framework for human activity beyond Earth’s atmosphere. It declares outer space, including the Moon and other celestial bodies, to be the province of all mankind, open for exploration and use by every country for the benefit and interest of all.29United Nations Office for Outer Space Affairs. The Outer Space Treaty The treaty’s central arms control provision bars any country from placing nuclear weapons or other weapons of mass destruction in orbit around the Earth, installing them on the Moon or any other celestial body, or stationing them in outer space by any other means. No nation can claim sovereignty over any celestial body, and exploration must avoid harmful contamination.30U.S. Department of State. Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies
Sovereign Immunity and Its Commercial-Activity Exception
A longstanding principle holds that a sovereign state cannot be sued in the courts of another country without its consent. That rule has eroded significantly for commercial activities. Under U.S. law, the Foreign Sovereign Immunities Act carves out exceptions where a foreign government can be sued in an American courtroom. The most important exception applies when the lawsuit arises from commercial activity carried on in the United States, or from an act performed abroad that causes a direct effect in the United States.31Office of the Law Revision Counsel. 28 USC 1605 – General Exceptions to the Jurisdictional Immunity of a Foreign State When a foreign government enters the marketplace as a buyer, seller, or investor, it takes on the legal obligations that apply to everyone else in that market.