What is “international law” and who enforced it?
“International law” is the set of treaties, compacts, and conventions to which various nations have all agreed. It is enforced through lawsuits and through international regulatory agencies, such as the World Trade Commission, the International Criminal Court, or the like. Sometimes, the suits can be filed in a country’s domestic courts, as well as the courts of the other nation, as well.
International laws are laws that multiple countries agree to, and can be enforced by the courts of those countries.
For example, the Patent Cooperation Treaty is a treaty between 152 countries, and if a country’s patent office violates a term of the treaty, that patent office can be sued in the country of that patent office.
However, not all treaties create enforceable rights. Some just contain memorandums of understanding and state an idealized goal. Others may create enforceable rights, but courts in those countries may make it difficult or impossible to enforce those rights due to procedural requirements. As is the case in almost all aspects of law, the devil is in the details.
The involvement of UN forces during the breakup of Yugoslavia is noted as being one of the first times the international criminal court was enacted, a large number of NATO countries led military strikes against slobidan melosavic (iirc the action came from the UN but the Russian block supported the Serbs who were winning and weren’t keen on disrupting that, meaning NATO Nations did much of the actual enforcement).
It’s a concept decided upon by people with large armies and economies so they don’t have to constantly fight each other to settle their disagreements, and to keep smaller countries in line. It’s enforced (erratically) by countries with large armies and economies through economic penalties and the threat of military force.
Don’t believe this “enforced by the courts” stuff- no court is capable of enforcing a decision against a Great Power if that power didn’t feel like complying. Notice that China and the US frequently ignore their theoretical treaty obligations and no enforcement occurs other than someone going “Tut tut” about it.
It’s an agreed set of standard laws which nations agree upon to some extent. It’s not actually enforceable but most civilised nations will take action to discourage acts which go against international law. This will probably be done to maintain international relationships.