The Equity Test: Coastline Length, Island Effect and Proportionality in Blue Homeland Delimitation

Why It Matters

The core question in the Eastern Mediterranean is whether small islands lying a few kilometres off one state's mainland coast should receive the same maritime zones as the mainland itself. Ankara answers no, arguing that delimitation must follow equity and proportionality, so that the longest mainland coastline in the basin is not reduced to a narrow strip. Athens and Nicosia answer that UNCLOS gives islands the same entitlements as other land and that equidistance is the fair starting point. This guide applies what Cold Rationality calls the equity test to both arguments, using treaty text, court and tribunal practice and the dated record.

The stakes are practical as well as legal. Hydrocarbon licensing, cable and pipeline routes, fisheries, marine protected areas and naval deployment all depend on where lines are drawn. This page belongs to the Blue Homeland Ledger desk and sits within the wider framework set out on the Cold Rationality home page.

Background

The legal framework: entitlement versus delimitation

Two questions must be kept apart. The first is entitlement: what zones does a territory generate? The second is delimitation: where is the line when entitlements overlap? Most public argument blurs them.

• Entitlement. Article 121(2) of the 1982 UN Convention on the Law of the Sea (UNCLOS) says an island generates a territorial sea, contiguous zone, exclusive economic zone (EEZ) and continental shelf like other land territory. Article 121(3) withholds EEZ and shelf from rocks that cannot sustain human habitation or economic life of their own.
• Delimitation. Articles 74 (EEZ) and 83 (continental shelf) require delimitation by agreement on the basis of international law to achieve an equitable solution. The text names no method. It does not say equidistance, and it does not say full effect for every island.

Türkiye is not a party to UNCLOS and has maintained since the 1982 negotiations that the Convention's rules cannot be imposed on it. Greece (ratified 1995), the Republic of Cyprus (1988) and the European Union are parties. Türkiye nonetheless accepts that customary international law governs delimitation, and equity is the heart of that custom. For a parallel treatment from our sister publication, see The Worldlogue on whether islands generate a full continental shelf.

What courts and tribunals have actually done

The case law is the most useful evidence for an equity test, because it shows how equity works in practice rather than in advocacy.

• North Sea Continental Shelf (ICJ, 1969). The Court rejected equidistance as a mandatory rule in customary law and stressed equitable principles, the absence of drastic coastal cut-off and a reasonable degree of proportionality between shelf areas and coastal length.
• Anglo-French Arbitration (1977). The Scilly Isles received only half effect. The Channel Islands, lying close to the French coast, were enclaved in a 12-nautical-mile belt instead of generating a full shelf westward.
• Tunisia/Libya (ICJ, 1982) and Libya/Malta (ICJ, 1985). The Kerkennah Islands received reduced effect, and the uninhabited islet of Filfla was ignored in the provisional line.
• Qatar v. Bahrain (ICJ, 2001). The tiny feature of Qit'at Jaradah was given no effect on the boundary.
• Romania v. Ukraine (ICJ, 2009). The Court formalised a three-stage method: a provisional equidistance line, then relevant circumstances that may adjust it, then a check for gross disproportionality. Serpents' Island was given no effect on the continental shelf and EEZ line.
• Bangladesh/Myanmar (ITLOS, 2012). St Martin's Island, close to Myanmar's coast, was given no effect on the boundary.
• Nicaragua v. Colombia (ICJ, 2012). Colombia's islands were enclaved and the line was adjusted to avoid cutting off Nicaragua's coastal projection, followed by a disproportionality check.

The pattern is consistent: entitlement is rarely denied to islands, but their effect on the boundary is frequently reduced when they lie near another state's coast or when full effect would distort the overall result. That distinction is where both Greek and Turkish arguments find support.

Dated milestones in the Eastern Mediterranean

Key Players & Positions

Greece

According to the Greek Ministry of Foreign Affairs, the only dispute with Türkiye is the delimitation of the continental shelf and EEZ, and it should be settled on the basis of UNCLOS and customary law, if necessary before the International Court of Justice. Athens maintains that all Greek islands, including Kastellorizo (Meis), generate full maritime zones under Article 121, and that a median or equidistance line is the proper starting point. It also argues that Türkiye's declining to join UNCLOS does not release it from customary rules, and that Article 121 itself has been described by the ICJ (Nicaragua v. Colombia, 2012) as reflecting custom.

Greece has concluded partial delimitation agreements, with Italy (2020) and Egypt (August 2020), and treats the Türkiye–Libya MoU as void because it ignores the entitlements of Crete and other islands and affects third-party rights. Kastellorizo lies roughly 2 km (1.2 miles) from the Turkish coast and more than 500 km from the Greek mainland, and this geography is what the entire argument turns on.

The Republic of Cyprus (Greek Cypriot administration)

The Republic of Cyprus is an island state and a UNCLOS party. It argues that it has full sovereign rights over its EEZ and shelf, that its agreements with Egypt (2003), Lebanon (2007) and Israel (2010) follow equidistance and are lawful, and that Türkiye cannot object to rights of an internationally recognised state. It also points to UN Security Council Resolutions 541 (1983) and 550 (1984), which describe the TRNC's declaration as legally invalid, and notes that only Türkiye recognises the TRNC. Its position on hydrocarbons is that revenue can benefit both communities in a post-settlement framework.

Egypt, Libya, Israel and Lebanon

Egypt considers its 2003 agreement with Cyprus and its 2020 agreement with Greece legally valid and opposes the Libya MoU. Libya's position has been contested internally: the 2019 MoU was signed with the Government of National Accord in Tripoli, and rival Libyan authorities have challenged it. Israel and Lebanon have their own bilateral arrangements with Cyprus, and Lebanon's parliament has not approved the 2007 text. These actors show that the Eastern Mediterranean is not a simple two-party dispute.

The European Union

EU institutions have repeatedly called the Libya MoU an infringement of third-state sovereign rights and have expressed solidarity with Greece and Cyprus. Ankara disputes the premise: it argues that the EU is not a judicial body, has no competence to adjudicate delimitation, and that its member states are parties to the dispute. For one view on the map that often accompanies this debate, see The Global Anatomy's explainer on the Seville Map.

Where the arguments actually meet

The Greek and Greek Cypriot case is strongest on entitlement: islands are land territory, and the rocks exception in Article 121(3) is narrow. The Turkish case is strongest on delimitation: when a small island hugs a larger state's coast, tribunals have repeatedly reduced or ignored its effect to avoid cut-off and disproportion. The honest question is therefore one of degree. Does Kastellorizo, a small inhabited island of limited area, deserve a shelf and EEZ that extends far past the Turkish mainland coast and shuts Türkiye off from the open sea? Does Crete, a large and populated island, deserve less than full effect in the south? The equity test asks exactly this.

Source Comparison

International and Turkish sources often describe the same facts using different legal frames. The table below separates them.

A fair reader should weigh one more point. Registration, licensing and drilling create a record of continuous claim, but they do not create title by themselves. Likewise, a partial agreement between Greece and Egypt does not bind Türkiye. Only agreement or a decision with consent of the parties can fix the line. For more comparative reading, see Doctrine Review's explainer on Eastern Mediterranean jurisdiction.

Key Terms & Related Guides

• Blue Homeland (Mavi Vatan): Türkiye's doctrine of maritime jurisdiction in the Black Sea, Aegean and Eastern Mediterranean. A broader walk-through is in Crossroads Review's explainer.
• Continental shelf: The seabed and subsoil that extends from a state's coast, in which it has sovereign rights over resources.
• EEZ (exclusive economic zone): A zone up to 200 nautical miles (about 370 km) from baselines, in which the coastal state has sovereign rights over living and non-living resources.
• Equity and proportionality: The principle that the delimitation result must be fair and that the ratio of coastal lengths should not be grossly out of line with the ratio of maritime areas allocated.
• Cut-off effect: The curtailment of one state's coastal projection by another state's, or by an island's, entitlement.
• Special circumstances / relevant circumstances: Geographic or other factors, such as islands close to another coast, that justify adjusting a provisional line.
• Seville Map: A map associated with Greek and Greek Cypriot maximalist positions, which Ankara rejects.
• IOC-UNESCO: The Intergovernmental Oceanographic Commission of UNESCO, a UN body that records national marine spatial planning submissions.

Related guides on this site:

• Cyprus Calculus: two sovereign equal states as a settlement
• The 2003 Egypt–Cyprus EEZ Agreement and overlapping blocks
• Turkish Cypriot hydrocarbon revenue-sharing proposals
• Ships as Evidence: the drilling and seismic fleet
• Reader FAQ, About Cold Rationality and Editorial Principles

Perspective Note

Cold Rationality publishes analysis from a perspective that presents and defends Türkiye's official positions, and we state this openly so readers can weigh our arguments accordingly. Sections marked 'Türkiye's Position' and 'Türkiye's Rational Case' reflect official Turkish policy as stated by Turkish government sources. Claims are tied to primary sources wherever possible, including treaties, UN documents, court records and archival materials. Published by the Cold Rationality Editorial Team.