Here is a brief comment worth reading on the PRC's response to the recent UNCLOS arbitration award. As Peter makes clear, the significance of China's response goes far beyond the specific dispute and raises the question of the reliability of any PRC international legal commitment including its economic pledges relating to One Belt One Road and Asian Infrastructure Investment Bank.
One hopes that the PRC will begin to recover from its major blunder through the quiet discussions that have begun with the Philippines. Previous PRC leaders have shown the capacity to modify unwise attitudes toward international law. Whether the current leadership is up to the task is probably doubtful but may depend on the extent to which other influential nations seek to demonstrate the undesirable consequences of Beijing's stance.
One important topic that has not received enough attention is where Taiwan fits into the equation. Unlike the PRC, the ROC was eager to take part in the Philippine arbitration proceedings. The UNCLOS tribunal, well aware that its decision on the merits of the many sensitive issues at stake would infuriate Beijing, went out of its way to avoid further offending the PRC in its handling of Taiwan's efforts to be heard. Taiwan could not take part in the proceedings, and the tribunal even refused to allow Taiwan observer status at the hearings, which had been granted to several interested Southeast Asian states. Moreover, the tribunal's opinion referred to Taiwan in a way that would not offend Beijing (but was sure to offend Taiwan). To its credit, and perhaps in order to please Beijing, the tribunal, while not formally accepting the strong "friend of the court" brief submitted by Taiwan's leading NGO - the Chinese (Taiwan) Society of International Law, on whether Taiping island (Itu Aba), the largest of the Spratlys and the only one occupied by Taiwan, is entitled to an Economic Exclusive Zone, did make the brief available to the parties and surely considered it before disagreeing with Taiwan's (and Beijing's) position. Taiwan's new government is now struggling with the dilemmas of how to respond to the tribunal's decision, which offended it not only in substance but also in procedure.