The High Seas

In one line

The high seas belong to nobody, are open to everybody, and are policed by each ship's own flag State except in a handful of cases where any State may act.

In the wording a student can write in an exam: the high seas comprise all parts of the sea not included in the exclusive economic zone, the territorial sea or the internal waters of a State, or in the archipelagic waters of an archipelagic State. They are open to all States, no State may validly purport to subject any part of them to its sovereignty, and they are reserved for peaceful purposes. Ships are subject to the exclusive jurisdiction of their flag State, subject to defined exceptions of which piracy, the right of visit and hot pursuit are the most important.

Grotius wins

The freedom of the high seas is the surviving half of the argument set out in [The Law of the Sea]. Grotius argued in Mare Liberum in 1609 that the sea cannot be owned and must be open to all; Selden replied that it could be appropriated; and the compromise was that the coastal State takes the near sea and everybody shares the rest.

Four centuries later the near sea reaches two hundred miles and the rest is still shared.

The core rules

Article 86. The provisions of Part VII apply to all parts of the sea that are not included in the exclusive economic zone, in the territorial sea or in the internal waters of a State, or in the archipelagic waters of an archipelagic State. The article is a residual definition: the high seas are what is left over.

Article 87(1). The high seas are open to all States, whether coastal or land-locked. Freedom of the high seas is exercised under the conditions laid down by the Convention and by other rules of international law, and comprises, inter alia, both for coastal and land-locked States:

(a) freedom of navigation; (b) freedom of overflight; (c) freedom to lay submarine cables and pipelines, subject to Part VI; (d) freedom to construct artificial islands and other installations permitted under international law, subject to Part VI; (e) freedom of fishing, subject to the conditions laid down in section 2; (f) freedom of scientific research, subject to Parts VI and XIII.

Article 87(2) requires these freedoms to be exercised with due regard for the interests of other States in their exercise of the freedom of the high seas, and with due regard for the rights under the Convention with respect to activities in the Area.

Two things about the list. The words inter alia mean it is not exhaustive. And the last four freedoms are each expressly made subject to other Parts, so freedom of fishing on the high seas is a freedom to fish under conditions and not a freedom to strip the ocean.