South Asia maritime disputes

Publication October 2014


A tribunal has delimited the maritime boundaries of India and Bangladesh in the overlapping areas of their territorial seas, exclusive economic zones and the continental shelf in the Bay of Bengal. Welcomed by both parties, the clarity provided by the decision should accelerate exploration of oil and gas in the area.

In an award issued on July 7, 2014, a five-member tribunal constituted under the United Nations Convention on the Law of the Sea (the Convention) delimited the maritime boundaries of India and Bangladesh. For practitioners, this decision provides several good takeaways regarding the competing methodologies used to decide maritime boundary disputes, what ‘special circumstances’ will be taken into account in setting boundaries and the role of equity in the process.


Under the Convention, a coastal state has sovereignty over territorial seas up to 12 nautical miles (nm) from its coastline. Beyond this and for a distance of up to 200 nm, a state has sovereign rights over its exclusive economic zone (EEZ). Then, up to 350 nm from its coastline (or up to 100 nm past where the ocean reaches a depth of 2,500 metres), a state has exclusive exploitation rights on the continental shelf projecting from its land territory.

With overlapping territorial seas, the Convention provides that the boundary shall be an equidistance line between each state’s coastline unless “historical title” or “special circumstances” indicate otherwise. Within EEZs and the continental shelf, the resolution of any overlapping boundaries “shall be effected by agreement on the basis of international law…in order to achieve an equitable solution”.

In the Bay of Bengal, there is overlap between the territorial waters, EEZs and continental shelf of Bangladesh and India – a function of the land boundaries set during the 1947 partition of British India and the maritime boundaries established by the 1982 Convention.

Since 1974, Bangladesh and India engaged in 11 rounds of negotiations to attempt to delimit their maritime boundaries, all unsuccessful. In 2009, Bangladesh initiated the present arbitration proceedings under the Convention to settle the issue.

In 2012, in a separate proceeding, the International Tribunal of the Law of the Sea (ITLOS) resolved a similar maritime boundary dispute between Bangladesh and its opposite coastal neighbour, Myanmar.


The tribunal first resolved the appropriate methodology to apply to the dispute. Under the relevant articles of the Convention, as interpreted by jurisprudence from the ITLOS and the ICJ, the tribunal decided it should construct a provisional equidistance line, and then determine whether any special/relevant circumstances required adjusting this line to achieve an equitable result. As noted by the tribunal, this was the ‘most logical and widely practised approach’ and the one better suited to the ‘paramount objective’ of transparency and equitable results.

In adopting this methodology, the tribunal rejected Bangladesh’s proposed alternative angle-bisector method, which would have drawn straight lines along each party’s coasts, then bisected the angle so formed. The final line set by the tribunal did in fact closely resemble the angle-bisector line proposed by Bangladesh (a result criticised in the partial dissent of India’s appointed arbitrator, Dr PS Rao).

Special/relevant circumstances

Climate change/unstable coastlines

The tribunal rejected Bangladesh’s arguments that extreme coastal instability in the Bengal Delta – allegedly caused in part by climate change and rising seas – constituted a ‘special circumstance’. According to the tribunal, such an argument if accepted would frustrate the objective of determining a permanent and definitive maritime boundary: only the present geophysical conditions are of relevance. Natural evolution, uncertainty and lack of predictability as to the impact of climate change on the marine environment, particularly the coastal front of states, make all predictions concerning the amount of coastal erosion or accretion unpredictable. This decision should be of interest to states with a low-lying or unstable coastline.

Fishing rights

The tribunal also rejected Bangladesh’s argument that its population’s heavy dependence on fish from the Bay of Bengal would exacerbate the inequity of limiting it to the narrow territory produced by the provisional equidistance line. According to the tribunal, Bangladesh did not submit sufficient evidence to meet the stringent test necessary to rely on such a circumstance.

Concavity of its coast/cut-off effect

The tribunal did, however, accept Bangladesh’s argument that the concavity of its coast was a special circumstance that properly should be taken into account. In particular, the tribunal noted that this concavity produced an unreasonable “cut-off effect that prevented Bangladesh from “extending its maritime boundary as far seaward as international law permits”. To ameliorate this effect, the tribunal adjusted the provisional equidistance line so that Bangladesh received a larger share of the overlapping EEZ and continental shelf than it otherwise would have.


In the final step of its analysis, the tribunal considered whether its adjusted delimitation line yielded a disproportionate result in the EEZ and continental shelf. Comparing the relevant maritime space accorded to each party to the ratio of their relevant costal lines, the tribunal noted that Bangladesh was allocated approximately 106,613 square km and India approximately 300,220 square km. The resulting ratio – 1:2.81 – was deemed not disproportionate.

“Grey areas”

The maritime boundary established by the tribunal created a “grey area” within 200 nm of India, but outside 200 nm of Bangladesh. In this area, Bangladesh controls the continental shelf, but India controls the EEZ.

The only precedent for setting a boundary that established such a grey area is the 2012 ITLOS Bangladesh/Myanmar decision. Such a grey area results in non-exclusive rights – with Bangladesh having sea-bed rights but India rights to the water column above. As noted by the dissent, this could create conflict between the states in the future – the exact opposite of the stated goals of the Convention and accepted jurisprudence. While eliminating the “grey area” required only a few turning points in the adjusted equidistance line, the tribunal rejected this approach, arguing that that a line without turning points was easier to administer.

The role of equity in delimiting maritime borders

The overarching goal of the Convention in the resolution of maritime boundary disputes is to achieve an equitable result. This is done, principally, by consideration of special/relevant circumstances to adjust a provisional equidistance line. As stated by the majority in the context of the present case:

The Tribunal should seek to ameliorate excessive negative consequences the provisional equidistance line would have for Bangladesh in the areas within and beyond 200 nm, but it must not do so in a way that unreasonably encroaches on the entitlement of India in that area.

The tribunal emphasised, however, the limited extent to which equitable principles could be invoked:

The purpose of adjusting an equidistance line is not to refashion geography, or to compensate for the inequalities of nature…equity does not require that a State without access to the sea should be allotted an area of continental shelf, any more than there could be a question of rendering the situation of a State with extensive coastline similar to that of a State with a restricted coastline.

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