Where in the world is the Philippines? In other words, where does the Philippines have jurisdiction? Of what kind? Where does that jurisdiction end? Because the Philippines is an archipelago, that is, a nation of many islands, these questions apply importantly to the country's maritime regime. In contemporary terms, what is the extent of the Philippines’ territorial sea? Its exclusive economic zone (EEZ)? Its contiguous zone? Its continental shelf? From where does or should the Philippines measure its territorial sea, contiguous zone and exclusive economic zone? What is the character of the large expanses of sea between some islands of the Philippines? What is the nature of the Philippine claim to the Kalayaan Island Group? What about the Philippine claim to Sabah?

For most countries, questions similar to these and the answers to them are fairly straightforward. They have long been settled, and other countries have accepted, or at least acknowledged, those answers. However, in the Philippine case, many of the questions remain unanswered. Fierce, often arcane debates go on within the government, in the academic community, and, of course, with other, especially neighbouring, countries. Once in a while, the controversies erupt into public view. One example is the case of the agreement between the Philippine National Oil Company and the China National Offshore Oil Corporation on a Joint Marine Seismic Undertaking and the subsequent agreement among these two firms and their Vietnamese counterpart to convert it to a tripartite endeavour. Another is the new legislation on the baselines from which to measure the territorial sea, the contiguous zone, the extended continental shelf, and the exclusive economic zone. In a move to make the country's declared maritime jurisdiction compatible with the 1982 United Nations Convention on the Law of the Sea (UNCLOS), the new baselines law declares a “regime of islands” with respect to Scarborough Shoal and to the land features in the part of the South China Sea that the Philippines claims. Enactment of the law immediately elicited protests from China and Vietnam, both of which claim all of the Spratlys, as well as disagreement, for other reasons, from some Philippine academics and legislators. China also claims Scarborough Shoal, which it calls Huangyan.