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Treaty between the Government of Australia and the Government of the Republic of Indonesia establishing an Exclusive Economic Zone Boundary and Certain Seabed Boundaries, done at Perth on 14 March 1997

Treaty text    (PDF) 
This map is not part of the treaty, but shows the points and lines mentioned.

This treaty was never ratified and has not entered into force.

Date of Proposed Binding Treaty Action: early 1998 (ratification)

Date of Tabling of the Treaty Action: 26 August 1997

Reasons for Australia to take the proposed Treaty Action

The proposed Treaty will settle the maritime boundaries between Australia and Indonesia in those areas where there are no boundaries currently agreed and will provide Australia with security of jurisdiction over the relevant offshore resources south of those boundaries. The boundaries in the Treaty represent an equitable and fair outcome for Australia.

The Treaty will benefit the resources industry. For petroleum, finalisation of the seabed boundaries will allow the release of additional areas for exploration to the west of the Ashmore and Cartier Islands which have not been released because of uncertainty over jurisdiction. For fisheries, finalisation of the maritime boundary will give certainty and allow a long-term approach to the management of fisheries in the Arafura and Timor Seas and around Christmas Island.

More generally, the Treaty enhances stability and security in both bilateral and regional terms. The settling of the maritime boundary between Australia and Indonesia greatly reduces the potential for future disputes and serves as a model of bilateral cooperation in the region.

Legal Framework for Boundaries

Under the 1982 United Nations Convention on the Law of the Sea (UNCLOS), to which both Australia and Indonesia are parties and which entered into force in 1994, coastal States are entitled to a continental shelf and exclusive economic zone (EEZ) extending up to 200 nautical miles (nm) from the baselines from which the breadth of the territorial sea is measured. Where the geomorphological shelf (the natural prolongation of a coastal State's land mass) extends beyond 200 nm, a coastal State may claim an additional area of shelf within limits established under UNCLOS. The maximum extent of the continental shelf in these circumstances is determined by a complex set of rules (one of which generates a line known as the Hedberg line) but in no case can it exceed the greater of 350 nm from the baseline or 100 nm from the 2500-metre isobath (a line connecting all points lying at a depth of 2500 metres).

The coastal State exercises full sovereignty over its territorial sea, which has a maximum breadth of 12 nm, but has only certain "sovereign rights" over the continental shelf and EEZ, namely to explore and exploit, conserve and manage the natural resources. It also has jurisdiction to protect and preserve the marine environment and to undertake marine scientific research.

Where the baselines of opposite States are less than 400 nm apart, as is the case for Australia and Indonesia, EEZ and continental shelf claims may accordingly overlap and it then becomes necessary to delimit maritime boundaries in order to provide certainty of jurisdiction and thus a secure basis for the resources of the maritime zones to be exploited. Under Articles 74 and 83 of UNCLOS, delimitation "shall be effected by agreement on the basis of international law as referred to in Article 38 of the Statute of the International Court of Justice in order to achieve an equitable solution".

Australia and Indonesia had already conducted a series of maritime boundary delimitation negotiations over a period of more than 25 years since the late 1960s. In that period, three treaties were concluded:
bulletin May 1971, a treaty was signed settling the seabed (continental shelf) boundary in the Arafura Sea from west of Cape York to the north of Arnhem Land - the treaty entered into force in November 1973;

in October 1972, a further treaty was signed settling the seabed boundary from the end-point north of Arnhem Land in the previous treaty to a point to the south of West Timor but leaving a gap in the area of what was then Portuguese Timor - this treaty also entered into force in November 1973; and


in December 1989, the Treaty between Australia and the Republic of Indonesia on the Zone of Cooperation in an Area between the Indonesian Province of East Timor and Northern Australia (the Timor Gap Treaty ), which deals provisionally with the gap in the seabed area not covered by the second (1972) treaty was signed - it entered into force in February 1991.

Since October 1981, there has also been in operation a non-treaty status Provisional Fisheries Surveillance and Enforcement Line (PFSEL) covering jurisdiction over fisheries enforcement matters in the water column between continental Australia and Indonesia. In addition, there is a 1974 Memorandum of Understanding between Australia and Indonesia, under which Indonesians using traditional fishing practices are permitted to have access to a box-shaped area in the vicinity of the Ashmore Islands.

The net effect of the three treaties is that three areas have remained for maritime boundary>> delimitation:
bulletthe seabed and water column boundary between the Indonesian island of Java and the Australian Territory of Christmas Island;

the complete water column boundary between the Australian mainland and Indonesia; and


the extension of the seabed boundary between the Australian mainland and Indonesia west of the point reached in the 1972 treaty.

It is important to note that the treaties negotiated to date have treated the seabed differently from the water column. Primarily, this is because recognition of continental shelf jurisdiction in international law predated the recognition of EEZ jurisdiction. Recognition of the latter form of jurisdiction only occurred in the late 1970s. That is, the concept of the EEZ was not known to international law at the time of the negotiation of the 1971 and 1972 seabed treaties. Except in relation to the area between Christmas Island and Java, this Treaty continues to treat seabed jurisdiction separately from water column jurisdiction.

Australian and Indonesian officials held eight rounds of consultations on the three outstanding areas, commencing in April 1993.

Details of Boundaries

Three maps depicting the lines described below are annexed to the Treaty.

Christmas Island/Java Delimitation

Christmas Island is 186 nm from Java. Under international law, as reflected in Article 121 of UNCLOS, Christmas Island is entitled to generate the full range of maritime zones. Australia's claim extends to the median line, while Indonesia's proclaimed EEZ extends the full 200 nm from the Javanese coast allowing only a 12 nm territorial sea "bubble" around Christmas Island.

The maritime boundary between Christmas Island and Java is a combined water column/seabed boundary resulting in a single line. The boundary configuration in the new Treaty is an adjusted median line constructed by two straight-line segments extending from a point on the line of shortest distance between Christmas Island and Java (the 186 nm referred to above) to the intersection of the Indonesian and Australian EEZ boundaries with the high seas to the west and east of Christmas Island. The position of that point on the line of shortest distance is 38.75 nm from Christmas Island.

Where an isolated island of one country lies close to the much longer coastline of another country, it is consistent with international law and practice for the boundary to be located closer to the isolated island. In the circumstances the resultant boundary constitutes an equitable solution as contemplated by Articles 74 and 83 of UNCLOS.

Water Column Delimitation

Australia and Indonesia have both claimed 200 nm EEZs under UNCLOS, and accordingly there is a vast overlap in claimed jurisdictions in the Timor and Arafura Seas. It would have been difficult, if not impossible, to gain Indonesian acceptance of a final water column boundary which departed from the 1981 PFSEL in a manner substantially in Australia's favour. The Treaty accordingly confirms that line, with two changes to recognise the fact that Sandy Island (part of Scott Reef) and the Ashmore Islands are full islands within the meaning of Article 121 of UNCLOS. The first is the extension of the boundary westwards to join up with the junction of the claimed Australian and Indonesian EEZs with the high seas. The second change involves the boundary around the Ashmore Islands, which has been moved out to 24 nm, and is meridial to the south-west and radial to the north of the islands. This is a configuration more favourable (and administratively manageable) to Australia than the 12 nm radial boundary of the PFSEL.

Western Extension of the Seabed Boundary

The 1971 and 1972 seabed delimitation treaties were negotiated on the basis of international law as it then stood, which recognised a State's sovereignty over the resources of its adjacent continental shelf as flowing from the "natural prolongation" of the State's land territory into and under the sea. This approach naturally focused attention on the geomorphology of the seabed concerned. In the case of Australia and Indonesia, Australia's broad continental margin and the presence of the Timor Trough led to the boundary agreed under the 1972 seabed agreement being significantly north of a median line between the two countries in the Timor Sea, and thus favourable to Australia. That boundary stopped at a point known as A25, however, leaving the area to the west to be delimited at a future time.

Since 1972, international law has moved to encompass a distance-based criterion. Nevertheless, in Australia's view the natural prolongation principle remains relevant to the negotiation of seabed boundaries. The existence of separate seabed and water column lines is the result of the application of different legal principles to delimitation of the EEZ and continental shelf. The result of the separate treatment of seabed and water column delimitation is that Australia has areas of seabed jurisdiction in which jurisdiction over the superjacent water column remains with Indonesia.

The seabed line at its commencement at the western end recognises the maximum extension of the Australian continental shelf claimable under UNCLOS (line running north from A82 to A79 - the Hedberg line ). The line then moves east, following a median line between the respective seabed claims: the natural prolongation of Australia's land mass and the PFSEL in the case of Indonesia. It then moves south from point A51 to the PFSEL at point A50, whence a straight line is drawn to the westernmost point of the 24 nm radial boundary around the Ashmore Islands; the line follows the radial boundary around the islands until it intersects with a straight line drawn south from point A25, the concluding point of the 1972 seabed agreement.

Relationship of this Treaty to the Timor Gap Treaty

The Treaty does not cover the area of seabed that is the subject of the Timor Gap Treaty. That treaty, which established "provisional" arrangements for a period of at least 40 years from its 1991 entry into force, is working satisfactorily. The Treaty does, however, establish a water column boundary in the Timor Gap. Nothing in the Treaty affects the rights and obligations of either Party under the Timor Gap Treaty. Nor can anything contained in the Treaty or any acts or activities taking place pursuant to the Treaty affect the respective seabed rights claimed by each Party in the Zone of Cooperation established under the Timor Gap Treaty or prejudice the position of either Party on a permanent seabed delimitation in the Zone of Cooperation.


The Treaty establishes the areas in which each country may exercise sovereign rights and jurisdiction and also the nature of those sovereign rights and jurisdiction. There are special provisions which govern those areas where Indonesia's water column jurisdiction overlaps Australia's seabed jurisdiction. Subject to other provisions of the Treaty, in such areas:
bulletIndonesia exercises EEZ sovereign rights and jurisdiction provided for in UNCLOS in relation to the water column and Australia exercises continental shelf sovereign rights and jurisdiction provided for in UNCLOS in relation to the seabed;

the construction of any artificial island is subject to the agreement of both Parties; an artificial island may be removed by the Party with jurisdiction over it, but such removal must have regard to fishing, the protection of the marine environment and the safety of navigation;


Australia must give Indonesia three months' notice of the proposed grant of exploration or exploitation rights;


each Party must give due notice to the other of the construction of installations and structures and maintain a permanent means of giving warning of their presence;


in order to ensure the safety of navigation, each Party must remove any installation or structure which is abandoned or disused and whose construction it authorised, taking into account any generally accepted international standards established in this regard by the International Maritime Organisation; such removal must also have due regard to fishing and to the protection of the marine environment, with appropriate publicity given to the depth, position and dimensions of any installations or structures not entirely removed;


the Party constructing an artificial island, installation, structure or fish aggregating device has exclusive jurisdiction over it;


marine scientific research carried out or authorised by Australia must be notified to Indonesia, and vice versa ;


the Parties must take effective measures to prevent, reduce and control pollution of the marine environment;


each Party is liable in accordance with international law for pollution of the marine environment caused by activities under its jurisdiction;


any island within the meaning of UNCLOS which emerges after the entry into force of the Treaty will be the subject of consultations between the Parties with a view to determining its status;


neither Party may exercise its rights and jurisdiction in a manner which unduly inhibits the exercise of the rights and jurisdiction of the other; and


the Parties must cooperate with each other in relation to the exercise of their respective rights and jurisdiction.

It should be noted that the requirement for notice of the grant of exploration and exploitation rights, of the construction of installations and of the carrying out of marine scientific research is not a requirement to obtain permission in order to do any of these things.

If any single accumulation of liquid hydrocarbons or natural gas, or if any other mineral deposit beneath the seabed, extends across the seabed boundaries established by the Treaty, and the part of such accumulation or deposit that is situated one side of the line is recoverable in fluid form wholly or in part from the other side of the line, the two Parties must seek to reach agreement on the manner in which the accumulation or deposit is to be exploited and on the equitable sharing of the benefits arising from such exploitation.


Future Protocols etc

No provision is made in the Treaty for future protocols of any kind. It can be amended at any time, however, by the mutual consent of the Parties by means of a further instrument of treaty status.


Adoption of these new boundaries between Australia and Indonesia will require minor amendments to the Petroleum (Submerged Lands) Act 1967 and a new EEZ Proclamation under the Seas and Submerged Lands Act 1973.


The interests of the States and Territories were represented throughout the negotiations by the Solicitor-General of Western Australia, who was a member of the Australian delegation.

Consultations were held in Canberra, Melbourne, Perth and Darwin with a range of interested groups and individuals, including the petroleum and fisheries industries, members of law and geography faculties from several universities, the Northern Land Council, the Headquarters of the Northern Command of the Australian Defence Forces, East Timor support groups based in Darwin and relevant agencies from State and Territory Governments.

Invitations to the consultations were based on the known and likely interest in the Treaty on the part of industry groups, academics, environmental NGOs, aboriginal groups and State and Territory government agencies.

The Department of Primary Industries and Energy had kept the Australian Petroleum Production and Exploration Association (APPEA) informed, in general terms, of progress in the negotiations on the Treaty throughout.

Interest in the Treaty was particularly strong on the part of the petroleum and fishing industries in Western Australia and the Northern Territory (where in practical terms the effect of the Treaty will be strongest). These industries were keen to have explained how the Treaty will apply in areas of overlapping jurisdiction.

Withdrawal or denunciation

The treaty does not contain express provisions dealing with withdrawal or denunciation. (Maritime delimitation agreements do not normally contain such provisions.) It would be possible, however, for one Party to withdraw from the treaty at any time with the consent of the other Party (Vienna Convention on the Law of Treaties Article 54).

Contact Details: Sea Law and Ocean Policy Group
International Organisations and Legal Division
Department of Foreign Affairs and Trade, Canberra

The Timor-Leste Institute for Development Monitoring and Analysis (Lao Hamutuk)
Institutu Timor-Leste ba Analiza no Monitor ba Dezenvolvimentu
Rua D. Alberto Ricardo, Bebora, Dili, Timor-Leste
P.O. Box 340, Dili, Timor-Leste
Tel: +670-3321040 or +670-77234330
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