Hello, I’m Zhan Qingyun.

Let us look closely at where the Philippines filed its arbitration and how it used—pardon the rather subjective word—the flexibility of arbitration to maximize its position.

When the South China Sea arbitration began, an amusing phenomenon emerged: international organizations rushed to say they had nothing to do with it. Careless reporting created widespread misunderstanding. The International Court of Justice first clarified that it had not made the decision—it was a court, not an arbitral tribunal. Even the United Nations said the matter was unrelated to it.

Because proceedings took place in The Hague, many mistakenly thought the Permanent Court of Arbitration had rendered the award. It had not.

The PCA quickly explained that it supplied only premises and secretarial services. The actual decision-maker bore a long name: the arbitral tribunal constituted under Annex VII to the United Nations Convention on the Law of the Sea. It may sound somewhat makeshift, so let me explain what it was.

We once tried, perhaps unsuccessfully, to explain law’s authority and why people have a duty to obey it.

International law attracts still greater skepticism; some deny it is truly law at all. They argue that it does not bind states and that international affairs are often governed by power rather than rules.

International law is therefore an awkward but fascinating institution.

Its two principal sources are custom and treaties. Custom may sound absurd: what practice counts as custom, and when states follow different practices, whose becomes law?

Consider outer-space exploration and the International Space Station, an area once lacking treaties. What custom applied? Initially only the United States and Soviet Union had explored space or conducted human spaceflight, so their practices became customary international law. That seems strange—and helps explain how great powers acquired their dominant role in international law.

Treaties sound more reasonable and resemble the social-contract ideal of how law originates. Participation is voluntary. No convention inherently binds a state; it does so only after that state chooses to join and sign it, and after it enters into force under domestic law.

Who writes these conventions, who has the greater voice, and whether every accession is truly voluntary are separate questions.