The 1898 Treaty of Paris officially concluded the Spanish-American War, transferring sovereignty over the Philippines from Spain to the United States for twenty million dollars. The treaty delineated the Philippine archipelago using a rectangular polygon of geographical coordinates, known as Treaty Limits. However, ambiguities in transcribing map coordinates and historical island names, specifically regarding peripheral islands like Mangsee and Turtle Islands near Borneo, introduced diplomatic friction.
Spanish and American negotiators relied on draft charts that conflated local names and misspelled key geographic markers, creating uncertainty over whether certain southwest maritime features fell inside or outside the treaty's defined box. The United States subsequently recognized that these boundary lines were drawn hastily without precise hydrographic surveys. When the treaty was ratified, the United Kingdom, controlling British North Borneo, raised questions about jurisdiction over islands near the treaty border, leading to the 1930 Anglo-American Convention to explicitly clarify territorial boundaries.
Decades later, as the Philippines established its modern legal identity and sovereign maritime claims, international legal scholars and diplomats revisited these historical drafting errors. The original treaty polygon lines, initially meant as a gross territorial bound rather than precise maritime limits, became a focal point in constitutional debates regarding Philippine national territory, illustrating how minute clerical oversights during imperial treaty negotiations can cast long shadows over modern international relations.