From an academic perspective, overseas Chinese scholars of international law have many reasons why the South China Sea case, initiated by the Philippines, has eroded their "trust and passion" in international law.

First, the appeals of the Philippines are purely about maritime entitlement, while China insists that this is a sovereignty dispute, on which the PCA has no jurisdiction under the framework of the UN Convention on the Law of the Sea.

Second, the tribunal can only arbitrate under the precondition that both sides, China and the Philippines, authorize it to do so, in line with international law. But China has never asked for that, and international law says China did not have to do so.

They worked day and night on the text of the open letter, which is 12 pages and 2,500 words in length.

"We are courageous in challenging the doings of the tribunal and the Philippines in a professional fashion," says Chinese student Peng Qinxuan.

The letter also stated in detail that state consent is the basis of the compulsory arbitration, while the dispute between China and the Philippines is on territorial and maritime delimitation. The scholars say in the letter that much evidence has shown that the tribunal has abused the legal process and taken wrong actions.

(Reporter: Fu Jing, video editor: Huang Zeyuan)