After flexing its navy muscle in the disputed South China Sea waters with combat drills and firing live missiles during the military exercises, China is now questioning the neutrality of the judges deciding on the South China Sea dispute filed by the Philippines.

The ruling by The Permanent Court of Arbitration in The Hague is expected to be issued on 12 July over who has legitimate rights over the disputed waters. China has already made it clear that it does not accept or recognise any decision that the court will make.

More about the South China Sea dispute

Hong Kong's newspaper the South China Morning Post has noted that both Chinese officials and the media have questioned the neutrality of the judges, And the first person to be in the firing line is Japanese judge Shunji Yanai who picked the arbitrators for the case.

Liu Zhenmin, China's Foreign Vice Minister has questioned the "procedural justice" of the appointment and the operation of the tribunal in an article published in the Communist Party magazine Qiushi last week, SCMP said.

He said Yanai should not have been involved in the case, given the territorial and maritime disputes between China and Japan in the East China Sea and Tokyo's moves to exert its influence in the issue.

China has refused to take part in the arbitration proceedings. In its absence, four of the five arbitrators were appointed by Yanai, who at the time the case was filed by the Philippines in 2013, was the president of the International Tribunal for the Law of the Sea (ITLOS), established under the UN Convention on the Law of the Sea. The fifth arbitrator was named by the Philippines.

Japan China territorial tensions
A Chinese Coast Guard vessel is pictured on the disputed region of South China Sea Erik De Castro/Reuters file photo

Liu pointed out that one of the judges appointed by Yanai had ruled against a party holding a position similar to China in a previous case. "Leaving aside the obvious violation of procedural justice, we can hardly make a better explanation of Judge Yanai's motivation and purpose other than that he did it on purpose," Liu claimed.

Needless to say, Yanai is not exactly a favourite in China. According to SCMP, a commentary by China's Xinhua state news agency, described the former senior Japanese foreign ministry official as a "typical, rightist, hawkish figure." Yanai had also served as Japan's ambassador to Washington.

Xinhua also noted that in 2007, during Shinzo Abe's first term as Japan's prime minister, Yanai served as the chairman of a panel set up to advise Abe on his plan to amend the constitution to allow Tokyo to embark on military action overseas.

"South Korea also expressed its concerns over Yanai's presidency of ITLOS as it also has territorial disputes with Japan," Xinhua said.

According to a research report by the Chinese Initiative on International Law, a Hong Kong and Hague-registered NGO, soon after the appointment of the tribunal, Yanai was reported to have told Japanese TV NHK that the islands of Japan were under enemy threat. The research report claimed that although the "enemy" mentioned by Yanai was not explicitly named, it said such a statement was clear enough for China to raise concerns over his impartiality in the case.

Liu also raised concerns over the arbitrators in the case, claiming that none of the five judges —an African national and four Europeans — had knowledge of the history and international order of ancient East Asia.

The SCMP however noted that Yanai's involvement in the arbitration appointment could have been avoided altogether if China took part in the proceedings. If China agreed to be a party to the proceedings, it could have named one of the tribunal's arbitrators and jointly appointed the three others in agreement with the Philippines.