What does the international law state about the high seas?

In the high seas, the law is difficult to enforce. The open seas do not belong to the jurisdiction of any State; therefore, anything can happen: piracy, slave or drug trafficking, fishing without limits, destruction of living ecosystems of the high seas, including marine animals. The sovereignty of a state stops where the high seas begin. However, the 1982 United Nations Convention on the Law of the Sea (‘the Convention’ or ‘the UN Convention on the Law of the Sea‘) lays down certain minimum provisions designed to protect, inter alia, peace, human rights, or the protection of living ecosystems and marine animals.  

A state has sovereignty over both its own territory and over a part of the sea that extends beyond the territory of the state. In international law, this portion of the sea is called the ‘territorial sea’). According to Article 3 of the UN Convention on the Law of the Sea, the territorial sea width extends up to 12 nautical miles (19.3 km) from the shore (the coastline). In this area of the territorial sea, states have full sovereignty, being able to exercise all the rights arising from its sovereignty, in terms of water, soil, subsoil, air column (the right to explore and exploit all natural resources, the regulation of navigation, the application of security measures, environmental protection, customs, and sanitary control, etc).[1]

source: geografy.name

Beyond the territorial sea, there is the exclusive economic zone of a state that stretches over 200 nautical miles from the baseline of the territorial sea, and in this marine space, the coastal state has various sovereign rights (i.e., exploration and exploitation of natural, biological, and non-biological resources, the right to install artificial islands, installations, and equipment for scientific research, the right to protect and preserve the right of the sea).

Generally speaking, the sovereignty of a state stops where the high seas begin. Article 86 of the UN Convention on the Law of the Sea defines the high seas as the portion of the sea which is not included in either the exclusive economic zone or the territorial sea or the internal waters of a State. The high seas are not under the sovereignty of any State and their legal regime is subject to a minimum of provisions that gravitates around the principle of ‘freedom of the high seas’.

What does the principle of freedom of the high seas mean?

Article 87 of the UN Convention on the Law of the Sea provides, inter alia, that all states have openness to the high seas even if they are not coastal states. Thus, in the light of the UN Convention, States may exercise, inter alia, their freedom of navigation, their freedom of overflight, and, under certain conditions, the freedom of fishing, the freedom to construct artificial islands. The high seas can only be used for peaceful purposes and no state can subject part of the high seas to its sovereignty.

What is the legal regime of ships on the high seas?

Under Article 92 of the UN Convention on the Law of the Sea, States may sail under the flag of a single State and are subject, on the high seas, to the exclusive jurisdiction of that State. As regards criminal jurisdiction, the UN Convention provides that a criminal investigation may be initiated only before the authorities of the flag State or in the State of which that person is a national. Warships and ships used for a non-commercial public service have, under the Convention, complete immunity from jurisdiction from any State other than the flag State. However, acts of piracy committed by those ships are in the same way as acts committed by a private ship or aircraft. States are also obliged to cooperate in the fight against piracy, illicit drug trafficking, or the transport of slaves, and the Convention expressly provides that any refugee slave on a ship, regardless of its flag, is free ipso facto.

What does ONU Convention state about fishing in the high seas?

Although the UN Convention on the Law of the Sea introduces the right to fish on the high seas, the exercise of this right is subject to the conditions of conserving the living resources of the high seas, including marine animals.

[1]Năstase, A. and Aurescu, B., 2018. Drept internaţional public. 9th ed. Bucharest: C.H.Beck, p.230.