What does international law say about a people's right to self-determination?

International law has moved steadily toward the right of a people to determine their own political status, and it contains no prohibition on a people declaring independence. The two clearest modern statements, from the world’s highest court and from Canada’s Supreme Court, both point the same direction.

The highest court in the world found no prohibition on declaring independence

In 2010 the International Court of Justice, the principal judicial organ of the United Nations, was asked directly whether Kosovo’s declaration of independence violated international law. The court examined centuries of practice and answered, by a vote of ten to four, that “general international law contains no applicable prohibition of declarations of independence.” There is no rule of international law that forbids a people from declaring themselves independent. The court looked for the prohibition everyone assumes exists, and it was not there. It left open whether any positive right to separate exists, saying it was “not necessary to resolve” that question.

Territorial integrity is a rule between countries, not a cage for peoples

The Kosovo opinion settled a second point that opponents lean on. The principle of territorial integrity, the court held, “is confined to the sphere of relations between States.” In plain terms, territorial integrity governs how countries treat each other’s borders. It is not a rule that locks a people inside the state they happen to live in. It restrains foreign invasion. It does not bind a population to a government it no longer consents to.

The United States argued for this very result

This is the part that should end the debate. When the Kosovo question was before the International Court of Justice, the United States argued in favor of the position the court adopted, and the United States recognized Kosovo as an independent country the day after it declared. So the federal government’s own stated position in front of the world’s highest court is that international law contains no prohibition on declaring independence. Washington cannot argue one rule abroad and the opposite rule at home.

A clear vote creates a duty to negotiate

The other landmark is Canada’s. In 1998 the Supreme Court of Canada held that while a province cannot simply declare itself gone overnight, a clear majority on a clear question creates a constitutional obligation on the rest of the country to negotiate separation in good faith, enforced through politics rather than the courts. Such a result, the court said, would carry a legitimacy the rest of Canada would have to recognize. A free people who vote clearly to govern themselves are owed a negotiation, not a dismissal.

The whole framework shifted from borders to consent after 1945

These rulings did not appear from nowhere. Since 1945 the foundation of international legitimacy has moved from the sanctity of existing borders toward the consent of the governed. The principle is written into the law the United States helped author. The United Nations Charter, in Article 1, states one of its core purposes as developing friendly relations among nations “based on respect for the principle of equal rights and self-determination of peoples.” We should be candid that the Charter frames self-determination as a guiding principle and that its application to a wealthy region of a stable federal union is genuinely debated by lawyers. But the direction of the law is not debated. The world has spent eighty years deciding that peoples, not just states, hold rights.

The bottom line

International law contains no prohibition on a people declaring independence, the principle of territorial integrity applies between countries rather than against peoples, and a clear vote of the people earns a duty to negotiate. The federal government argued for exactly this when it suited Washington’s interests abroad. If it is lawful for Kosovo, it is lawful for Texas.