United Nations Convention on the Law of the Sea

The United Nations Convention on the Law of the Sea (UNCLOS), also called the Law of the Sea Convention or the Law of the Sea Treaty, is an international treaty that establishes a legal framework for all marine and maritime activities. As of October 2024, 169 sovereign states and the European Union are parties.
The convention resulted from the third United Nations Conference on the Law of the Sea (UNCLOS III), which took place between 1973 and 1982. UNCLOS replaced the four treaties of the 1958 Convention on the High Seas. UNCLOS came into force in 1994, a year after Guyana became the 60th nation to ratify the treaty. In 2023, agreement was reached on a High Seas Treaty to be added as an instrument of the convention, to protect ocean life in international waters. This would provide measures including Marine Protected Areas and environmental impact assessments.
While the secretary-general of the United Nations receives instruments of ratification and accession and the UN provides support for meetings of states party to the convention, the United Nations Secretariat has no direct operational role in the implementation of the convention. A UN specialized agency, the International Maritime Organization, does play a role, however, as do other bodies such as the International Whaling Commission and the International Seabed Authority (ISA), which was established by the convention itself.
United Nations Convention on the Law of the Sea replaces the older "freedom of the seas" concept, dating from the 17th century. According to this concept, national rights were limited to a specified belt of water extending from a nation's coastlines, usually 3 nautical miles (5.6 km; 3.5 mi) (three-mile limit), according to the "cannon shot" rule developed by the Dutch jurist Cornelius van Bynkershoek. All waters beyond national boundaries were considered international waters: free to all nations, but belonging to none of them (the mare liberum principle propounded by Hugo Grotius).
In the early 20th century, some nations expressed their desire to extend national claims: to include mineral resources, to protect fish stocks, and to provide the means to enforce pollution controls. The League of Nations called a 1930 conference at The Hague, but no agreements resulted. Using the customary international-law principle of a nation's right to protect its natural resources, President Harry S. Truman in 1945 extended United States control to all the natural resources of its continental shelf. Other nations were quick to follow suit. Between 1946 and 1950, Chile, Peru, and Ecuador extended their rights to a distance of 200 nautical miles (370 km; 230 mi) to cover their Humboldt Current fishing grounds. Other nations extended their territorial seas to 12 nautical miles (22 km; 14 mi).
By 1967, only 25 nations still used the old three nautical mile limit, while 66 nations had set a 12-nautical-mile (22 km) territorial limit and eight had set a 200-nautical-mile (370 km) limit. As of 15 July 2011, only Jordan still uses the 3-mile (4.8 km) limit. That limit is also used in certain Australian islands, an area of Belize, some Japanese straits, certain areas of Papua New Guinea, and a few British Overseas Territories, such as Gibraltar.
UNCLOS does not deal with matters of territorial disputes or to resolve issues of sovereignty, as that field is governed by rules of customary international law on the acquisition and loss of territory.
The United Nations Sustainable Development Goal 14 has a target regarding conservative and sustainable use of oceans and their resources in line with UNCLOS legal framework.
In 1958, the United Nations held its first Conference on the Law of the Sea (UNCLOS I) at Geneva, Switzerland. UNCLOS I resulted in four treaties concluded in 1958:
Although UNCLOS I was considered a success, it left open the important issue of breadth of territorial waters.
In 1960, the United Nations held the second Conference on the Law of the Sea ("UNCLOS II"); however, the six-week Geneva conference did not result in any new agreements. Generally speaking, developing nations and third world countries participated only as clients, allies, or dependents of the United States or the Soviet Union, with no significant voice of their own.
The issue of varying claims of territorial waters was raised in the UN in 1967 by Arvid Pardo of Malta, and in 1973 the Third United Nations Conference on the Law of the Sea convened in New York. In an attempt to reduce the possibility of groups of nation-states dominating the negotiations, the conference used a consensus process rather than majority vote. With more than 160 nations participating, the conference lasted until 1982. The resulting convention came into force on 16 November 1994, one year after the 60th state, Guyana, ratified the treaty.
The convention introduced a number of provisions. The most significant issues covered were setting limits, navigation, archipelagic status and transit regimes, exclusive economic zones (EEZs), continental shelf jurisdiction, deep seabed mining, the exploitation regime, protection of the marine environment, scientific research, and settlement of disputes.
The convention set the limit of various areas, measured from a carefully defined baseline. (Normally, a sea baseline follows the low-water line, but when the coastline is deeply indented, has fringing islands or is highly unstable, straight baselines may be used.) The areas are as follows:
The area outside these areas is referred to as the "high seas" or simply "the Area".
Aside from its provisions defining ocean boundaries, the convention establishes general obligations for safeguarding the marine environment and protecting freedom of scientific research on the high seas, and also creates an innovative legal regime for controlling mineral resource exploitation in deep seabed areas beyond national jurisdiction, through an International Seabed Authority and the common heritage of mankind principle.
The convention also established the International Tribunal for the Law of the Sea (ITLOS) in Hamburg, Germany.
Landlocked states are given a right of access to and from the sea, without taxation of traffic through transit states.
Part XI of the convention provides for a regime relating to minerals on the seabed outside any state's territorial waters or exclusive economic zones (EEZ). It establishes an International Seabed Authority (ISA) to authorize seabed exploration and mining and collect and distribute the seabed mining royalty.
The United States objected to the provisions of Part XI of the convention on several grounds, arguing that the treaty was unfavorable to American economic and security interests. Due to Part XI, the United States refused to ratify the UNCLOS, although it expressed agreement with the remaining provisions of the convention.
From 1982 to 1990, the United States accepted all but Part XI as customary international law, while attempting to establish an alternative regime for exploitation of the minerals of the deep seabed. An agreement was made with other seabed mining nations and licenses were granted to four international consortia. Concurrently, the Preparatory Commission was established to prepare for the eventual coming into force of the convention-recognized claims by applicants, sponsored by signatories of the convention. Overlaps between the two groups were resolved, but a decline in the demand for minerals from the seabed made the seabed regime significantly less relevant. In addition, the decline of communism in the late 1980s removed much of the support for some of the more contentious Part XI provisions.
In 1990, consultations began between signatories and non-signatories (including the United States) over the possibility of modifying the convention to allow the industrialized countries to join the convention. The resulting 1994 Agreement on Implementation was adopted as a binding international convention. It mandated that key articles, including those on limitation of seabed production and mandatory technology transfer, would not be applied, that the United States, if it became a member, would be guaranteed a seat on the Council of the International Seabed Authority, and finally, that voting would be done in groups, with each group able to block decisions on substantive matters. The 1994 Agreement also established a Finance Committee that would originate the financial decisions of the Authority, to which the largest donors would automatically be members and in which decisions would be made by consensus.
On 1 February 2011, the Seabed Disputes Chamber of the International Tribunal for the Law of the Sea (ITLOS) issued an advisory opinion concerning the legal responsibilities and obligations of states parties to the convention with respect to the sponsorship of activities in the area in accordance with Part XI of the convention and the 1994 agreement. The advisory opinion was issued in response to a formal request made by the International Seabed Authority following two prior applications the authority's Legal and Technical Commission had received from the Republic of Nauru and the Kingdom of Tonga regarding proposed activities (a plan of work to explore for polymetallic nodules) to be undertaken in the area by two state-sponsored contractors – Nauru Ocean Resources Inc. (sponsored by the Republic of Nauru) and Tonga Offshore Mining Ltd. (sponsored by the Kingdom of Tonga). The advisory opinion set forth the international legal responsibilities and obligations of sponsoring states and the authority to ensure that sponsored activities do not harm the marine environment, consistent with the applicable provisions of UNCLOS Part XI, Authority regulations, ITLOS case law, other international environmental treaties, and Principle 15 of the UN Rio Declaration.
Part XII of UNCLOS contains special provisions for the protection of the marine environment, obligating all states to collaborate in this matter, as well as placing special obligations on flag states to ensure that ships under their flags adhere to international environmental regulations, often adopted by the IMO. The MARPOL convention is an example of such regulation. Part XII also bestows coastal and port states with broadened jurisdictional rights for enforcing international environmental regulation within their territory and on the high seas.
The convention was opened for signature on 10 December 1982 and entered into force on 16 November 1994 upon deposition of the 60th instrument of ratification. The convention has been ratified by 170 parties, which includes 166 UN member states, 1 UN Observer state (Palestine), two non-member states (the Cook Islands and Niue) and the European Union.
The significance of UNCLOS stems from the fact that it systemizes and codifies the standards and principles of international maritime law, which are based on centuries of maritime experience and are expressed to a great extent in the United Nations Charter and current international maritime law norms, such as the Geneva Conventions of 1958. A large portion of these requirements were further strengthened and expanded.