About 300 Chinese legal experts gathered in Changchun, Jilin province to discuss the case. Their analysis was unanimous: China should abstain from participating in the case, because the arbitration panel has no jurisdiction over the dispute. They believed China has legitimate rights under international law to reject the arbitration.
“That is because the tribunal that arbitrates maritime disputes under the U.N. Convention on the Law of the Sea, has no jurisdiction over Manila’s claims,” China University of Political Science and Law Professor Ma Chenyuan said. “And the country’s unilateral initiation of the arbitration broke the agreement with us that the disputes should be resolved through bilateral negotiations.”
In October 2015, the Arbitral Tribunal at the Hague concluded that it has jurisdiction over the matters raised in seven of the Philippines’ claims.

http://www.cctv-america.com/2016/05/07/chinese-legal-experts-refute-philippine-claim-in-south-china-sea