The latter two derive their claim primarily based on prior discovery and historical use of the islands, and object to the Daioyus’ illegal cession during late-imperial times. Japan’s possession is based on a stricter reading of international law. The Senkakus were terra nullis when it took control of the islands in 1895. Further, because Japan was not deemed to have renounced sovereignty over the Ryukyus, as per the San Francisco Treaty of 1951, and because the trusteeship authority — the U.S. Civil Administration Of The Ryukyu Islands — which administered Okinawa in the post-war period included, in 1953, the Senkakus within its jurisdictional boundaries, Tokyo deems sovereignty over the Senkaku to have reverted back at the time of Okinawa’s reversion in 1972. Absent a binding legal instrument between Japan and China establishing a territorial boundary however, the final status of the island remains in dispute.

During the summer of 1996, both countries ratified the Law of the Sea treaty (UNCLOS). As part of its ratification, China refrained from specifying EEZ baselines around the islands’ waters; maintaining effective possession, Japan proceeded to base its EEZ claim as radiating out from the Senkakus, though it declined to specify its extent to the west and to the north, that is, vis-à-vis China.

Basic Sino-Japanese Fisheries Related Legalities, Understandings and Practices

Sino-Japanese fisheries issues in the disputed waters abutting the Senkakus/Daioyus derive from political understandings – and practices thereunder – that have accompanied the various bilateral fisheries agreements since 1955. Until 1975, these agreements were of a non-governmental nature, that is, between fisheries groups. Akin to its previous editions, the prevailing version — the bilateral Fishery Agreement of 1997, which went into effect in June 2000 – excludes the water area south of 27N (that is, areas around the Senkakus/Daioyus) from its recognised jurisdiction.

However, bearing the disputed islands in mind, Japan and China exchanged a Note Verbale, as part of the 1997 agreement, stating that in defense of ‘traditional practices,’ flag – not coastal – state laws would apply to fisheries vessels operating in waters south of 27N. This explicit political understanding was designed to politically skirt the issue of application of coastal state jurisdiction, including the exercise of fisheries-related policing in EEZ waters, arising from Japan’s drawing of its claimed territorial sea and EEZ baselines from the islands. Additionally, as part of the 1997 agreement, a (inherited) Joint Fishery Committee is empowered to consult on matters, among others, that relate to this water area south of 27N.

Because both parties claim the Senkakus/Daioyus to be their own, no commonly agreed legal restraints exist insofar as the right to fish in the immediate 12 nautical mile territorial sea abutting the islands. By way of subsequent practise though, Chinese fisheries vessels have been required to stay beyond the 12 nm territorial sea limit, and those that enter are escorted out. That PRC state vessels do not challenge this exclusion but correspondingly limit their furthest point of ingress to the 12 nm contiguous zone that abuts the territorial sea, suggests that they implicitly too accept this prevailing fishing order in the ‘area surrounding the islands.’

As such, while bilateral fisheries-related legalities broadly exclude the waters around the Senkakus/Daioyus from its jurisdiction, written political understandings that flow from the agreement do stipulate flag jurisdictional authority in these waters. Flag state authority issuing from these understandings has been limited in practise though in the immediate 12 nm ‘territorial sea’ of the Senkakus/Daiouyus.

Analysis of Japanese Decision-Making in light of the Prevailing Maritime Regime

In detaining the captain and crew, Tokyo committed no illegality – either as signatory to the 1997 Fishery Agreement or as effective administrator of the islands. The 1997 agreement excludes the islands from its legal purview; as effective administrator, it is wholly within Japan’s prerogative to use all necessary means to establish an order of peace on the islands and in its 12 nm environs. Further, while the waters south of 27N, including those surrounding the Senkaku islands can be construed by third parties, technically, as being the ‘high seas’ – given its lack of settled legal enclosure, for the two parties concerned, the incident occurred within waters that are wholly claimed to be ‘territorial’. As such, the consistency of Japan’s actions with regard to UNCLOS-related provisions related to ‘high seas’ jurisdiction is not directly relevant to this incident.

In arresting the Chinese captain and weighting the evidence towards indictment, Japan, again, committed no illegality. As effective administrator of the islands, Japan is within its rights to treat all breaches occurring on the islands or its territorial seas as a matter subject to domestic law. The Note Verbale exchanged with China in 1997 notwithstanding, Japan at no point of time has consented to a de jure limitation on its right to freedom of judicial action in Senkaku territorial seas – for activities allegedly criminal or otherwise.

That said, in arresting the Chinese captain and weighting the evidence towards indictment, Japan might have violated the political aspects of the understandings that flowed from the 1997 Fishery Agreement. Under this regime, flag-state laws (that is PRC jurisdiction), not coastal state laws, were deemed to apply to fisheries-related activities in the ‘area surrounding the islands.’ By the same token though, Tokyo can plausibly argue that the ‘malicious’ nature of the Chinese captain’s actions debarred him from protections afforded in the Note Verbale which were meant to be restricted to fisheries-related infringements, not criminally-liable acts. It is arguable, moreover —albeit less plausibly so, that the fisheries regime is too underdeveloped or ambiguous in the immediate 12 nm territorial seas zone for it to carry any real political weight.

What is not in controversy, however, is that by arresting the Chinese captain and weighing prosecution, Japan was preparing to set an altogether new precedent. Tokyo has applied domestic law previously in the Senkakus against a foreign entity caught breaking the law, most recently in 2005 when the Koizumi government detained Chinese-origin intruders prior to their expulsion. It has never previously though threatened indictment and prosecution of such law-breakers in a domestic court of law. In doing so, Japan was setting a consequential precedent in the exercise of jurisdiction over contentious territory that it knew was held in dispute, and, in the process, taking a significant diplomatic risk.

Though presumably alerted to this course of action by the degree of malice involved in the Chinese captain’s behaviour, Tokyo’s approach, politically, was contrary to the decades-long, commonly agreed principle of shrewdly building separation between sovereignty/territorial and fisheries-related issues in the disputed Senkaku waters. While Tokyo has been prudent in assuming a more activist posture to regional maritime jurisdictional issues over the past half-decade or so, to use the admittedly reckless behavior of a private Chinese citizen to re-assert this posture on this occasion was not wise.

Rather than prolong the detention beyond the initial 10-day period with the sword of indictment hanging over the skipper’s head, Tokyo ought to have treated the incident as a fisheries issue, taken advantage of the ambiguous language contained in the Note Verbale (or the opportunity to delegate down aspects of the controversy to the Joint Fishery Committee), and thereafter expelled the offending fisherman. The consequences of the failure to promptly do so continue to weigh negatively on Japan’s politics and diplomacy to this day.

Sourabh Gupta is a senior research associate at Samuels International Associates, Inc and a contributor to EAF.