As the Second World War waned, delegates from 50 nations convened in San Francisco to draft the founding document for what would become the leading international organization in the world. They signed the Charter of the United Nations on June 26, 1945, and it took effect on October 24 of that year. Among other provisions, the Charter establishes the equality of sovereign states and strictly limits the use of force in international conflicts.

The 193 members of the United Nations each have committed to abide by the principles in the Charter. Becoming a member requires accepting these obligations and getting approval from current UN members. The Security Council must recommend that a nation become a member, and then the General Assembly must approve the recommendation. A 60 percent vote is required in the Security Council and a two-thirds vote in the General Assembly.

The International Law Center at Justia explains this membership process and describes each of the major organs in the UN, such as the General Assembly, the Security Council, and the Secretariat. It also provides a separate discussion on the International Court of Justice, which emerged from the San Francisco Conference as well. The Court consists of 15 judges, who are elected to nine-year terms by the General Assembly and the Security Council. The ICJ serves two main functions. First, it resolves disputes between nations by applying principles of international law. In addition, it issues advisory opinions to public international organizations, including several UN organs. While its judgments in disputes between nations are binding, ICJ advisory opinions are not binding. Still, they tend to carry substantial weight.

Armed Conflicts Under International Law

Having endured two world wars, the drafters of the UN Charter sought to reduce the risk of future global conflagrations. Article 2(4) of the Charter severely restricts the use of force by UN members against other nations. (It does not apply to the use of force within a nation and likely does not apply to the use of non-military force.) However, a nation may use force in response to an armed attack by another nation under Article 51 of the Charter. This codifies the principle of self-defense in traditional international law. Similar to individual self-defense, national self-defense needs to be proportionate to the act of aggression.

When war proves inevitable, international humanitarian law controls how it should be conducted. The main rules stem not from the UN Charter but instead from the Geneva Conventions of 1949. Other international agreements address specific concerns like the use of chemical and biological weapons. International humanitarian law establishes rights for non-combatants in places under the control of another nation’s military forces, as well as rights for former combatants like prisoners of war. It also prohibits certain methods of waging war, such as those that cannot distinguish between military and civilian targets.

Human Rights & The Environment

Since adopting a Universal Declaration of Human Rights in 1948, the UN has sought to bolster civil, political, economic, social, and cultural rights. In 2006, the General Assembly replaced the Commission on Human Rights with a more robust Human Rights Council. Among other duties, it reviews human rights issues in each UN member state every four years. The High Commissioner for Human Rights has the authority to respond to violations. Committees in the Human Rights Council monitor the implementation of human rights treaties, aiming to ensure that nations honor their obligations after ratifying a treaty. International human rights organizations also operate at regional levels, complementing UN efforts with their own rules and enforcement mechanisms.

The UN seeks to protect the environment as well, recognizing that nations cannot solve problems like global warming independently. The first UN Conference on the Human Environment produced the Stockholm Declaration of 1972, which articulated 26 principles of international environmental law. More recently, agreements like the Kyoto Protocol and the Paris Agreement have targeted the looming concern of climate change. For example, nations that ratified the Paris Agreement pledged to keep the average temperature of the Earth from rising above a certain ceiling. Environmentalists hope that it achieves success similar to the Montreal Protocol of 1987, which has helped restore the ozone layer in the stratosphere.

International Agreements Under U.S. Law

The Supremacy Clause of the U.S. Constitution provides that treaties made under the authority of the United States are the supreme law of the land. Not every international agreement is formally considered a treaty under U.S. law. To qualify for this status, it must receive the approval of two-thirds of the Senate. If the President makes an international agreement without the approval of two-thirds of the Senate, this is considered an “executive agreement” instead of a treaty. While an executive agreement may not fall within the Supremacy Clause, it still may preempt state laws due to federal power over foreign affairs.

Some provisions in international agreements are considered “self-executing,” which means that they automatically take effect as enforceable U.S. law. On the other hand, a provision that is not self-executing cannot be enforced until Congress passes implementing legislation. However, the question of whether a provision is self-executing affects only the domestic enforcement of the provision, rather than U.S. obligations under international law.

Final Thoughts

Developing legal principles to govern nations across the globe is not easy. Enforcing compliance with those principles can be even more difficult. Still, international agreements and organizations have helped make our planet a better place. The International Law Center at Justia discusses the progress that has been made, while acknowledging the challenges that remain. Like the other Justia Legal Guides, it aims to make the law transparent and accessible to all.