The Chinese traditional maritime boundary line in the South China Sea and its legal consequences

3    The Chinese traditional maritime boundary line in the South China Sea and its legal consequences


The South China Sea is a semi-enclosed sea under the definition set down in the United Nations Convention on the Law of the Sea (LOS Convention).1 It has an area of 648,000sq nm, twice the area of the Sea of Japan.2 There are hundreds of small islands in the South China Sea, namely uninhabited islets, shoals, reefs, banks, sands, cays, and rocks.3 They are distributed widely in the form of four groups of islands and underwater features, i.e. the Pratas Islands (Dongsha Qundao), the Paracel Islands (Xisha Qundao), the Macclesfield Bank (Zhongsha Qundao), and the Spratly Islands (Nansha Qundao). It is interesting to note that in Chinese these groups of small islands have a big name, “qundao” – archipelago. Such a nomenclature is questionable in law and/or in geography,4 particularly for the Macclesfield Bank that is permanently submerged under the water, though a common Chinese view has considered Scarborough Reef part of the Macclesfield Bank.5 If such a view were generally accepted, then the English name should be changed to “Macclesfield Islands”,6 like those of the other three groups. However, a detailed discussion of this is beyond the scope of this chapter.

The political situation in the South China Sea is complicated, as it contains the potential for conflict of different national interests. In terms of the islands groups, because of their geographical differences, their political situations accordingly differ from each other. The Pratas Islands are under the firm control of the Taiwan Chinese. No competing claims exist there under the concept of “one China”. For the Macclesfield Bank, the only claimant is China including Taiwan.7 However, if Scarborough Reef is to be considered part of the Macclesfield Bank, then recent developments show that the Philippines, having lodged its territorial claim over the reef, has also in effect made a claim over the Macclesfield Bank. The Paracel Islands are under the control of China, though contested by the Vietnamese. Because of the firm control by the Chinese, the political situation around the Paracels is relatively calm and stable in comparison with that around the Spratly Islands. The dispute over the Spratly Islands is the most complicated since it has been ongoing for a long time and involves as many as five states, i.e. China including Taiwan, Malaysia, Vietnam, the Philippines, and Brunei. It is unusual in the history of international relations that so many countries make claims, either in whole or in part, over the small islets of the Spratly Islands and their surrounding water areas. As many predict, if the issue of the Spratly Islands is not well handled, it could constitute a threat to the peace and security of East Asia and of the world. In China’s view, the issue of boundaries and sovereignty over areas of the South China Sea is one of the three main factors that might trigger military conflicts in the Asia-Pacific Region.8

There are many issues involving the Spratly Islands, such as the territorial claims, historic rights, strategic considerations, military mobility, free navigation, and control of natural resources. The Chinese maritime boundary line (hereinafter referred to as “the line”) has added complexity to the issues.9 It refers to the line with nine segments off the Chinese coast on the South China Sea, as displayed in the Chinese map. It has several varied names, such as the U-shaped line,10 nine-interrupted-lines,11 the nine-dashed intermittent line,12 the line of “national boundary”,13 the “dotted-line”,14 “the tongue-shaped line”,15 as well as “the Chinese border”.16 These different names are somewhat confusing. People may query what the line means and what is significant about it. Does China claim all within the line as its national territory, including the islands, underwater rocks, the seabed as well as the water columns?

Although there is a wealth of literature on the South China Sea and the Spratly Islands, the Chinese traditional boundary line has yet to be assessed in detail. This chapter intends to make a relatively thorough assessment of this line in a legal perspective so as to contribute to the building-up of the South China Sea legal literature and to facilitate understanding of the significance of the line by the world community.

Origins and evolution of the line

The line first appeared in the map in December 1914, which was compiled, according to some known sources, by Hu Jinjie, a Chinese cartographer.17 The maps published during the 1920s and 1930s followed Hu’s drawings.18 The line at that time only included the Pratas and the Paracels. It began from the Sino-Vietnamese land boundary next to the Gulf of Tonkin, extended southeastwards offshore of the Vietnamese coast, then ran eastwards to the west side of the Island of Luzon, then northeastwards along the east side of the Pratas, through the Taiwan Strait, and finally met the Chinese boundary line to the East China Sea and the Yellow Sea. The southernmost end of the demarcation was located at about 15° and 16° north latitude.19 However, no reasons were given why the line should have been drawn like this and for what purposes.

The year of 1933 seems to have been an important time for the modification and emphasis of the line in Chinese maps. In July that year, France, the then protector of Vietnam, occupied nine small islands of the Spratly Islands. This action was strongly protested by China, and afterwards the line in the maps relating to the South China Sea extended further south to 7° to 9° north latitude.20 The intention behind this was clear: to indicate clearly that the Spratly Islands belonged to China. However, the James Shoal (Zengmu Ansha) was not included. While the line at that time on most of the maps was drawn between 7° and 9° north latitude, there was at least one atlas collection, the New China’s Construction Atlas, edited by Bai Meichu and published in 1936, which included the James Shoal into the line, i.e. further extended the line to 4° north latitude. In 1935, the Committee of Examining the Water and Land Maps of the ROC published the names of 132 islets and reefs of the four South China Sea archipelagos. The publication had an annexed map which marked the James Shoal at the location of about 4° north latitude, 112° east longitude, though there was no demarcation of the line on the map. It indicated that the then Chinese Government considered the southernmost territory of China to be at 4° north latitude.21 It is therefore clear that Bai took the Committee’s publication as the basis for the line in his compilation.

It should be noted that all the atlases including the line were compiled by individuals. They may, however, constitute indirect evidence to show the official position of the Chinese Government. It was not until 1947 that the line was officially confirmed by the Chinese Government. On 1 December 1947, the Chinese Ministry of Interior renamed the islands in the South China Sea and thus formally allocated them into the administration of the Hainan Special Region.22 Meanwhile, the ministry also prepared a location map of the islands in the South China Sea, which was released for internal use. In February 1948, the Atlas of Administrative Areas of the Republic of China, in which the above map was included, was officially published. This is the first official map to include the line and it has had a substantial influence over the subsequent maps either published by the mainland or by Taiwan. It has two general characteristics: the southernmost end of the line was set at 4° north latitude including the James Shoal; and the 11-segment line was used instead of the previous continuing line. According to the then official explanation, the basis for drawing the line was that:

The southernmost limit of the South China Sea territory should be at the James Shoal. This limit was followed by Chinese governmental departments, schools and publishers before the anti-Japanese war, and it was also recorded on file in the Ministry of Interior. Accordingly it should remain unchanged.23

It is unclear whether the explanation refers to the line or to the southernmost territory of China, and before the anti-Japanese war there were a few atlases that marked the line at about 4° north latitude. The notable compilation was Bai Meichu’s edition. It is thus hard to say that the southernmost limit was already consistently followed in practice. The situation remained unclear. On the other hand, the explanation did not give the reasons why the line was drawn this way. Despite all these doubts, however, the line on the map has been accepted ever since in Chinese practice. What then are the implications of the line?

We may assume that there must be some reasons behind the drawing of such a line, though we have no clear official explanation. We can see from history that each extension of the line from the north to the south was a reaction to the challenges or encroachments made by foreign intruders to the Chinese claims of sovereignty and jurisdiction of the islands in the South China Sea. Originally it should not be necessary to draw such a line on the maps if there were no disputes over the ownership of the islands. The first time when the line appeared on the map was in 1914, just after the recovery of the Pratas Islands from the Japanese.24 The second extension was triggered by the French occupation of some islets of the Spratly Islands. The final extension happened when China received the Paracels and Spratlys from the defeated Japan after World War II. Since sovereignty and jurisdiction over the offshore islands were relatively weak, to draw a line on the map was just a means of consolidating China’s sovereign control over these islands.

Since there is no official explanation for the line, commentators may explain it in their own way. Thus different views and opinions have arisen. The next section looks at evidence from China’s recent practice which may be helpful for the explanation of the line.

China’s attitudes towards and practice within the line: the mainland and Taiwan

Maps officially published both in the mainland and Taiwan take the same position regarding the line, since both sides have succeeded to the official map published in 1947. In addition, the Chinese of both sides have military and economic activities within the line. There are also a number of relevant laws and official documents that have legal implications for the line.

After the Chinese Communist Party took over the mainland in 1949 and established the PRC, the map of the South China Sea was the same as before 1949. During the 1960s, there were a few small modifications: the two segments in the Gulf of Tonkin were removed from the map and the line then had nine segments. Beijing did not give a public explanation of why the two segments were removed from the map, but it might have been related to the transfer of the sovereignty over the Bai Long Wei Island in the Gulf of Tonkin from China to Vietnam.

In 1958, China promulgated the Declaration on China’s Territorial Sea, in which China declared that the Dongsha Islands, the Xisha Islands, the Zhongsha Islands, and the Nansha Islands all belonged to China.25 Although the Declaration did not mention the line in the South China Sea, it had some implications for the line. First, the Declaration says that between the mainland and its coastal islands and the archipelagos in the South China Sea, there exist certain areas of the high seas. Second, it provides that the method measuring the Chinese territorial sea of 12nm by straight baselines for the mainland and its coastal islands is also applicable to the archipelagos in the South China Sea.26 The above principles are reaffirmed in China’s Law on the Territorial Sea and the Contiguous Zone promulgated in 1992.27 In May 1996 China publicized part of its baselines along the mainland coast and the Paracel Islands by the method of straight baselines. China decided 28 basepoints to encircle the Paracels and the surrounding waters.28 The waters within the baselines are internal waters and from the baselines outward there is also a belt of territorial sea of 12nm. In the same statement, it is declared that China will decide other baselines in due time, including the baselines for the Spratly Islands.

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