Can a world court actually force a country to obey its ruling?

No, not on its own. The International Court of Justice, nicknamed the World Court, is the United Nations' main judicial body, and its rulings on disputes between countries are final and binding on the parties. But the court has no formal enforcement mechanism. If a country ignores a ruling, enforcing it becomes a political matter for the UN Security Council, and since each of the five permanent members holds a veto there, a single one of them can block enforcement.

That isn't hypothetical. When the court ruled that the United States' covert war against Nicaragua violated international law, the United States withdrew from the court's compulsory jurisdiction, and when Nicaragua took the noncompliance to the Security Council, the United States used its veto.

The court's roots go back to the 1899 Hague Peace Conference, initiated by Russian Tsar Nicholas II, which created the Permanent Court of Arbitration. A 1907 attempt to create a permanent court with full-time judges fell apart because nobody could agree on how to choose them. The League of Nations cracked that problem in 1920 with the Permanent Court of International Justice, whose judges were elected independently by two League bodies. The United States helped set it up but never joined, even though several Americans served as its judges.

Today's ICJ, founded in 1945 as that court's successor, sits in the Peace Palace in The Hague, the only principal UN organ not based in New York. Every UN member state is automatically a party to its statute, but that is not the same as accepting its authority over a specific case: a country must separately consent before the court can rule on a dispute involving it. Since its first case in 1947, its 15 judges, elected for nine-year terms with no two from the same country, have heard more than 200 cases.