State Territory

Boundary rivers and lakes. Where a river separates two States the boundary is usually the thalweg, the line of the deepest channel or the main navigable channel, in a navigable river, and the median line in a non-navigable one. The thalweg rule exists so that neither State controls the whole navigable channel.

Airspace

Article 1 of the Chicago Convention 1944 states the rule: the contracting States recognise that every State has complete and exclusive sovereignty over the airspace above its territory. The words complete and exclusive are the point, and they contrast sharply with the sea: there is no right of innocent passage through airspace, so an aircraft needs permission.

Airspace above the territorial sea is included; airspace above the exclusive economic zone and the high seas is not, and is open to all. All of this is [International Air Law].

How high does it go? No agreed boundary. The territorial airspace stops somewhere and outer space begins, and no treaty says where. The usual working figure is the lowest altitude at which a satellite can maintain an orbit, around 100 kilometres, sometimes called the Karman line, and it is a convention rather than a rule. The reason it has never been settled is that neither the air powers nor the space powers gained by settling it.

Article II of the Outer Space Treaty 1967 settles the other side: outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means. So territory stops before space begins, wherever the line is, and this is [International Space Law].

Things that travel

Ships and aircraft are not territory, and calling them floating or flying territory is an error students make and examiners punish. They have the nationality of a State, dealt with in [Nationality], and the flag State exercises jurisdiction over them. The Lotus case is the authority: the freedom of the seas allows a State to assimilate a ship flying its flag to its own territory for penal purposes, without giving it exclusive jurisdiction over a collision.

Embassies are not territory either. An embassy is in the receiving State's territory. Its premises are inviolable, which is a rule about what the receiving State's officials may do, not a transfer of sovereignty. A child born in a foreign embassy in Delhi is born in India.

What sovereignty over territory means

The classic formulation comes from the case worked in the next chapter: sovereignty in the relations between States signifies independence, and independence in regard to a portion of the globe is the right to exercise therein, to the exclusion of any other State, the functions of a State.

Three practical consequences.

Exclusivity. No other State may perform acts of authority in the territory without consent. That is why the Corfu Channel minesweeping was a violation even though the mines were a menace, and it is worked in [Innocent Passage, and Straits].

Responsibility. With exclusivity comes the duty not to allow the territory to be used for acts contrary to the rights of other States, and the duty to warn of dangers known to exist there. This is [State Responsibility].

It must be maintained. The Island of Palmas award holds that the continuous and peaceful display of territorial sovereignty is as good as a title, and that effectiveness is required not only for acquisition but equally for maintenance.

Limitations on territorial sovereignty

Sovereignty over territory is exclusive; it is not unlimited. Five standing limitations.

Innocent passage through the territorial sea, which the coastal State cannot refuse to ships generally.

Servitudes, rights another State holds over the territory: a right of transit, of fishing, of using a port, or an obligation not to fortify an area, usually created by treaty.

Treaty limitations generally: demilitarisation, neutralisation, base agreements, and the rights other States hold in international rivers and canals.

The rules on the use of force. Territory may not be acquired by force, and the fact that it is territory does not make what happens there nobody else's business.

International concern. Human rights obligations, environmental obligations and the obligation not to cause harm to another State's territory all restrict what a State may do at home.

A worked example

State A and State B are separated by the navigable River Zed. A cargo vessel of State C sails up the river, then out to sea through State A's territorial sea, and an aircraft of State C flies the same route overhead. State A objects to both.

Where is the river boundary? The thalweg, the main navigable channel, unless a treaty or long practice fixes it elsewhere. Each State is sovereign up to that line.

May the ship pass through State A's territorial sea? Yes, provided the passage is innocent. Article 2 makes the territorial sea sovereign territory and expressly subjects that sovereignty to the Convention, and innocent passage is what the Convention provides. State A may regulate the passage but cannot forbid it generally.

May the aircraft fly over the same water? No, not without permission. Airspace above the territorial sea is territorial airspace, and article 1 of the Chicago Convention gives the State complete and exclusive sovereignty over it. There is no innocent passage in the air, and this is the single most useful contrast in the chapter.

Once the ship is fifty miles out, what changes? It is in State A's exclusive economic zone, where State A has sovereign rights over resources but no sovereignty, so navigation is free. The aircraft may fly there too: airspace above the exclusive economic zone is not territorial. Those zones are [The Exclusive Economic Zone] and [The High Seas].

Where does State A's airspace stop going up? Nowhere that any treaty states. It is generally taken to end around the lowest perigee of a satellite orbit, roughly 100 kilometres, and article II of the Outer Space Treaty puts everything above it beyond appropriation.

Distinctions table

What it does NOT mean

A ship is not floating territory. It has the nationality of its flag State, and the flag State's jurisdiction follows from that. Lotus says the assimilation is for penal purposes and is not exclusive.

An embassy is not the sending State's territory. Its premises are inviolable; sovereignty remains with the receiving State.

Sovereignty is not unlimited. Innocent passage, servitudes, treaty limitations, the prohibition of force and obligations of international concern all bind the territorial sovereign.

Territory is not only land. Leaving out internal waters, the territorial sea, the subsoil and the airspace answers a quarter of the question.

Limits and criticism

The upper limit of airspace is genuinely unsettled, more than sixty years after the first satellite, because no State has needed it settled badly enough to accept a rule that constrains it.

The thalweg rule is unstable, because rivers move. Where a boundary river shifts, the boundary may or may not move with it, and the answer depends on whether the change was gradual accretion or a sudden avulsion, which is a distinction taken from the law of property and imported into the law of territory.

Effectiveness sits awkwardly with legality. Palmas makes continuous and peaceful display as good as a title, which is a rule that rewards the State in possession. The modern prohibition on acquiring territory by force pulls the other way, and the two meet in [Acquisition of State Territory].

Quick revision

Territory is the portion of the globe subject to a State's sovereignty: land, subsoil, internal waters, territorial sea with its bed and subsoil, and the airspace above all of them.

UNCLOS article 8: internal waters are the waters landward of the baseline. Sovereignty there is complete and there is no innocent passage.

UNCLOS article 2: sovereignty extends to the territorial sea, its bed and subsoil and the airspace above it, and is exercised subject to the Convention, which is why innocent passage exists.

Chicago Convention article 1: every State has complete and exclusive sovereignty over the airspace above its territory. No innocent passage in the air.

Outer Space Treaty article II: outer space is not subject to national appropriation. The upper limit of airspace is undetermined; the working figure is about 100 km.

Boundary rivers: the thalweg, the main navigable channel, in a navigable river; the median line otherwise.

Ships and aircraft are not territory; they have nationality. Embassies are not territory; their premises are inviolable.

Sovereignty means the right to exercise the functions of a State to the exclusion of any other, and Island of Palmas holds it must be continuously and peacefully displayed, not merely acquired.

Test yourself

1. What does the territory of a State comprise?

The land within its frontiers and the subsoil beneath, its internal waters, its territorial sea together with the bed and subsoil beneath that, and the airspace above all of them. Article 2 of the Convention on the Law of the Sea states the position for the sea and the air above it, article 8 defines internal waters as those on the landward side of the baseline, and article 1 of the Chicago Convention states the rule for airspace.

2. Contrast the position of a foreign ship in the territorial sea with that of a foreign aircraft in the airspace above it.

The ship has a right of innocent passage, which the coastal State may regulate but not generally deny, because article 2 makes the coastal State's sovereignty over the territorial sea subject to the Convention and the Convention confers that right. The aircraft has no corresponding right: article 1 of the Chicago Convention gives every State complete and exclusive sovereignty over the airspace above its territory, and an aircraft may enter only by permission, whether under a bilateral agreement or a general one. The contrast is the clearest illustration that different parts of one territory carry different rules.

3. Is a ship the floating territory of its flag State?

No. A ship has the nationality of the State whose flag it flies, and the flag State exercises jurisdiction on that footing. The Lotus case put it precisely: the freedom of the seas allows a State to assimilate a ship flying its flag to its own territory so far as penal jurisdiction is concerned, without giving it, as regards collisions, any more extended right amounting to exclusive jurisdiction. Territory and nationality are different bases of jurisdiction and the metaphor confuses them.

4. Where does a State's airspace end?

There is no agreed answer, and no treaty fixes it. The usual working figure is the lowest altitude at which a satellite can maintain an orbit, about 100 kilometres, sometimes called the Karman line, but it is a convention among writers rather than a rule of law. What is settled is the position above: article II of the Outer Space Treaty 1967 provides that outer space, including the Moon and other celestial bodies, is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means.

5. Name four limitations on territorial sovereignty.

The right of innocent passage through the territorial sea, which the coastal State cannot deny to shipping generally. Servitudes, being rights another State holds over the territory such as transit, fishing or port use, or obligations such as not to fortify. Treaty limitations generally, including demilitarisation, neutralisation and rights in international rivers and canals. And the general limitations of international law: the prohibition of the acquisition of territory by force, and obligations of international concern in human rights and the environment, including the duty not to allow the territory to be used for acts contrary to other States' rights.

6. Explain the thalweg and why it is used.

The thalweg is the line of the deepest channel, or in practice the main navigable channel, of a river. Where a navigable river forms the boundary between two States, the boundary follows the thalweg rather than the middle of the river, so that neither State controls the whole navigable channel and both retain access. In a non-navigable river the median line is used instead, since there is no navigation interest to protect.