One of the major deadlocks in Turkish-Greek maritime disputes is the fact that Turkey is not party to the United Nations Convention on the Law of the Sea (UNCLOS). Nonetheless, Greece insists on a resolution of the disputes only under the principles of this convention, including its stipulations on the breadth of the territorial sea and islands’ capacities to generate Exclusive Economic Zones. Greece has long taken a stance arguing that if Turkey believes in international law, it should first sign UNCLOS, show respect for international law, and then come to the negotiation table. This approach lacks basic legal foundations.
While true that the rest of the world widely accepts the principles recognized by UNCLOS, also known as the “constitution of the oceans”, just because Turkey did not sign the pact doesn’t mean it can be labelled an outlaw in contempt of world order. Contrary to other conventions, UNCLOS does not allow reservations; states are required to accept the package deal in its near entirety. Apart from the articles on the “breadth of the territorial sea” (TS) and the “regime of islands”, Turkey actually recognizes the validity of the Convention and its nature of customary law. Turkey’s initial objection to the Convention primarily stemmed from the existence of the some 2,000 Greek islands in the Aegean Sea, and it did not sign UNCLOS on this basis.
The regime of islands and the 12 nautical mile (nm) breadth of the TS have become part of customary international law. Whether party to UNCLOS or not, all states are bound by the rules of customary international law, with one exemption: the persistent objector. Indeed, rules of customary international law cannot be imposed on a state that has persistently and clearly objected to the development of the rule since its emergence. This is because international law essentially depends on consent of the state. Turkey has done whatever needed to be a persistent objector to the development of customary rules on the regime of islands and the breadth of the territorial sea.
Expansion of the Law of the Sea
With the signing of the Treaty of Lausanne, Aegean islands were ceded to Greece in 1923. The Treaty defined Turkey-Greece land borders, and decided the sovereignty of the islands. Parties did not define their maritime boundaries, as there was no such common concept at the time. Rather, they referred to a 3-nm belt of water beyond the Turkish shore, and practiced a 3-nm TS. The idea was to keep the rest of the Aegean Sea as international waters.
In the 1920s, the international community was busy codifying laws on the land. Maritime law was not at the forefront of the agenda. In 1923, when the Treaty of Lausanne was signed, neither Greece nor Turkey anticipated that maritime law would change so significantly and that the high seas of the Aegean would one day be nationalized. At that time, questions mostly revolved around the distribution of land between the parties.
But the second half of the 20th century saw significant progress in the law of the oceans. New concepts and doctrines evolved and existing coastal claims expanded seaward, with strong implications for today’s Turkish-Greek maritime dispute. Meanwhile, the initial maritime balance in the Aegean Sea was not sustained and was consistently altered in favour of Greece.
Expansion of the Territorial Sea

Since the early teachings of the first legal philosophers there has been a consistent trend in the law of the seas towards the extension of the limits of coastal state jurisdictions. Hugo Grotius, the father of international law, advocated for the freedom of the seas in the 17th century, with the exception of a small belt of water adjacent to the shore, the so-called TS. The breath of the TS was often measured by the range of a cannon or by visibility.
In 1782, legal scholar Galiani suggested a 3-mile limit, which became the growing norm in state practice in the 19th and early 20th centuries. At the 1930 Hague Conference, 20 states advocated for a 3-mile limit, while 12 states suggested a 6-nm TS. At the Second UN Conference on the Law of the Sea in 1960, the majority of states suggested a 6-mile TS. With the 1982 UNCLOS, the 12-nm limit was firmly established in state practice and international law.
Birth of the Contiguous Zone
When the Treaty of Lausanne was signed, the concept of the Contiguous Zone (CZ) did not exist. This doctrine was essentially developed during the prohibition era in the US to prevent foreign vessels from violating its prohibition laws. In the 1920s, over one hundred vessels anchored directly outside of the US’s 3-nm TS daily, while small boats smuggled alcohol into US territory. These ships donned foreign flags, were anchored in international waters, and benefited from international immunity.
In order to enforce its national laws and combat smugglers, the US introduced a CZ to control an area up to 12-nm from its shores. Many foreign vessels were seized at the time. Nonetheless, from the 1930 Hague Conference to the 1958 Geneva Conferences, many states claimed similar jurisdictions contiguous to their TSs. The Geneva Conferences agreed on the existence of the CZ for the purpose of preventing the “infringement of [the state’s] customs, fiscal, immigration or sanitary regulations”. States practiced CZs varying from 3-nm to 9-nm until UNCLOS, which finally recognized a 24-nm outer limit for CZ claims.
Emergence of the Continental Shelf
Another blow to the principle of the freedom of sea was the emergence of the legal concept of the continental shelf (CS). Advanced technologies capable of extracting offshore energy resources from the seabed led to the development of this legal regime. The ability to exploit gas and oil resources from the sea did not begin until three decades after the signing of the Treaty of Lausanne, and it has rapidly advanced since the 1950s.
In 1945, the Truman Proclamation officially gave birth to this legal concept. Between 1945 and 1958, many states claimed CS jurisdictions. The Truman Proclamation did not define the breadth of the CS, but the 1958 Geneva Convention codified this regime and adopted a 200-meter depth or exploitability criteria. Finally, in 1982, UNCLOS defined the outer limit of the CS as 200-nm, and up to 350-nm in exceptional circumstances.
Development of the Exclusive Economic Zone
Developments in the 1970s and the new world order following decolonization led to yet another significant regime, the exclusive economic zone (EEZ). The evolution of this doctrine was an attempt by developing states to reserve natural resources off of their coasts, keeping them from exploitation by developed states. They were afraid that fish stocks and resources would be exhausted before they even had the chance to advance their technologies and capabilities enough to exploit them themselves. It is not a coincidence that this concept was first introduced by Kenya, and gained rapid support across Africa, Asia, and Latin America.
However, developed states were concerned about the expansion of coastal jurisdictions, as they wanted the oceans to remain open to freedom of navigation. The EEZ was an acceptable compromise between these two groups: it gave extensive economic rights to coastal states and it preserved the freedom of navigation and overflight to the benefit of third parties. In a very short period of time, the EEZ became the rule of customary international law, and was finally codified as a 200-nm zone with UNCLOS in 1982.
Implications for the Turkish-Greek Dispute

As explained above, since the Treaty of Lausanne, there has been a consistent trend in the law of the sea towards the extension of the limits of coastal state jurisdiction. When the Treaty of Lausanne was signed, over 99% of the world’s oceans were high seas. With the universal establishment of 200-nm EEZs, today, over one third of the world’s seas and almost 90% of fish stocks and natural resources now fall under coastal jurisdiction.
For the most part, the evolution of the law of the sea has had an acceptable outcome for much of the world. While some states significantly benefited from this legal environment, such as those with islands, others have not enjoyed the same advantages, particularly landlocked or geographically disadvantaged states. Among all, Turkey is the one state most dramatically disadvantaged by the current framework. Due to the particularities of its unique geography, there is no other coastal state that has been so grossly and negatively impacted by the evolution of international law of the sea as Turkey. The Aegean Sea is the only maritime area where thousands of islands belong to one state in a semi-closed narrow sea, encroaching upon a 1,000-km long coastline of another state. Some of these islands are only a few km from the Turkish shoreline.
In an open sea, or where parties have a balanced geographical presence, the extension of the TS would normally benefit both parties, at the expense of third parties. While this is the case for the rest of the world, it does not produce the same result in the Aegean Sea. The extension of the TS from 3-nm to 6-nm in the Aegean Sea has already positioned half of this sea under Greek sovereignty. With the potential expansion of the TS to 12-nm, the status of the Aegean Sea would be even more drastically altered to the extreme detriment of Turkey (See Map).
Are New Rules Binding for Turkey?
From hunting alcohol smugglers and using advanced technology to exploit seabed resources, to protecting fish stocks from rich countries… none of these historical events are native to the Aegean Sea nor do they apply to the realities of the region. Nonetheless, they severely distort the Aegean’s maritime balance and fundamentally undermine the foundational understanding established between Turkey and Greece when they signed the Treaty of Lausanne.
Are these new legal developments binding for Turkey? Does it have to accept these new norms? The answer is a resounding “no”! Not because these developments are detached from the realities of the Aegean Sea, but because of universally recognized legal norms.
The principles of “sovereign equality” and “free consent of states” require that states are equal and free to decide their neighbourly relations. The principle of “pacta sunt servanda” indicates that every treaty in force is binding for those party thereto, and the obligations instituted therein must be honoured in good faith. The principle of “exclusive jurisdiction” provides that a country is not bound by the new rules of international law, unless by its own express or implied consent.
Greece and Turkey freely settled their land borders with the Treaty of Lausanne and sustained a maritime balance. No authority or third party has the right to dictate otherwise. Turkey has indeed been trying to argue this case, but it has been going about it incorrectly. Instead of resting on these solid legal principles, it declared that Greece’s TS expansion would be a casus belli, questioned the sovereignty of Greek islands, and brought about maximalist claims that lack legal ground, including those enclosed in the Turkey-Libya maritime agreement.
Turkey’s Options
Being a persistent objector does not automatically exempt Turkey from the general rules of international law that are universally recognized by UNCLOS and jurisprudence. Turkey is still bound by the firmly established principles of maritime law as crystallized in case law. It needs to refrain from maximalist claims contradicting these principles.
Instead, Turkey’s position as a persistent objector means that it has an inherent legal right to reject certain norms when it comes to the Aegean dispute, particularly with regard to the breadth of the TS. In simple terms, while Greece has a customary right to extend its TS up to 12-nm in the Aegean, Turkey also has the right to reject and not recognize this potential declaration. By the same token, a court will neither denounce the right of Greece to extend its TS to 12-nm nor will it impose a 12-nm TS on Turkey.
Islands’ capacity to generate CSs and EEZs is a separate topic from the breadth of TS. On the regime of islands, international courts have already addressed similar concerns, and downgraded the islands’ effects vis-à-vis mainland territories. Since the Romania-Ukraine delimitation case in 2009, odds have started to shift in Turkey’s favour, and Turkey shouldn’t be afraid to take the case to court.
If the parties commence international adjudication for the delimitation of EEZs in the Aegean Sea, courts would apply equitable principles. The generosity that Article 121 of UNCLOS grants to islands would not prevail, and the vast majority of Greek islands in the Aegean Sea would be deemed to have partial to no effect on the Anatolian coast.
Having said that, even were such a favourable judgment to be passed, the vast majority of the maritime area would still fall under Greek jurisdiction. Turkey should not expect to control half of the Aegean Sea in any scenario. At the end of the day, thousands of Aegean islands belong to Greece.
Equity and legality do not always infer the same meaning. In this sense, the Turkish-Greek maritime dispute is a perfect case study within the sociology of international law. But the question remains: must legal norms correspond to equitable principles, or can they be extremely detrimental to one party while overtly favouring the other in a comparable situation?
Yunus Emre Acikgonul is an independent lawyer and legal researcher. He has published multiple articles in international law journals, written a book, and shared his expertise on the law of the sea with several media outlets. Two of Acikgonul’s most recent academic studies were selected and published in the “Ocean Yearbook” and “Canadian Yearbook of International Law” along with the other highest-rated articles of the year.