Why did China reject the 2016 arbitration ruling on the South China Sea?

China rejected the 2016 arbitration ruling regarding the South China Sea primarily by denying that the arbitral tribunal had the legal jurisdiction to hear the dispute.1

By refusing to participate in the proceedings, China maintained that the tribunal’s award was "null and void" and possessed "no binding force," explicitly stating that it would neither accept nor recognize the decision. China’s position is rooted in its assertion that its claims to the region are based on "historical waters," which it argues supersede the United Nations Convention on the Law of the Sea (UNCLOS) boundaries cited by the tribunal.213

The tribunal, however, ruled that the "nine-dash line" was invalid and that UNCLOS provisions take precedence over China's historical claims in areas of conflict. Despite the ruling, China continues to assert its sovereignty over these maritime areas, maintaining a persistent presence through its coast guard and military infrastructure.21