The Sino-Philippine Arbitration on the South China Sea Disputes was over on July 12, 2016, with a Merits Award in Philippine favor. Beijing rejected this arbitration and abstained from submitting written and oral arguments. Taiwan actively engaged in the debate with the Philippines since July 7, 2015. Not deemed as representative of China, Taiwan was considered capable of clarifying the meaning of the U-Shaped Line it first published in 1947 when seated in Nanjing, representing China then. The biggest maritime feature in the Spratly Islands, i.e. Taiping Island (Itu Aba), has been occupied by troops from mainland China since 1946 and then from Taiwan since 1956. The legal status of Taiping Island was the key to success of Philippine Submissions. The factual information from Taiwan became vital. This paper examines Taiwan’s role in this arbitration and the degree to which it could actually speak for China at such legal proceedings.

1. Introduction
 2. Development of SCS Arbitration
  A. Initiation of the Arbitration
  B. The Philippine Memorial and Written Arguments
  C. The Jurisdictional Award
  D. Second Hearing and the Amended Submissions
  E. The Merits Award
 3. Taiwan’s Role in the SCS Arbitration
  A. The Initial Stage
  B. Taiwan Factor in the Philippines’ Memorial and Written Arguments
  C. Taiwan’s Official Statements on July 7, 2015
  D. New Contentions of the Philippines in November Hearings
  E. Taiwan’s Further Statements and Amicus Curiae Brief
  F. The Philippines’ Responses to Taiwan’s Further Arguments
  G. The Merits Award and Taiwan
 4. Conclusion

• Michael Sheng-ti Gau(Professor of International Law at the Institute for the Law of the Sea, National Taiwan Ocean University.)