Maritime Zones

Concept and Constitutional Setting

Maritime zones are the belts of sea, seabed, subsoil, airspace, and related marine areas over which a coastal or archipelagic State may exercise sovereignty, sovereign rights, jurisdiction, or limited enforcement authority. They translate territorial sovereignty over land into measured legal entitlements at sea.

The Philippine national territory includes the Philippine archipelago, all other territories over which the Philippines has sovereignty or jurisdiction, and the terrestrial, fluvial, and aerial domains connected with them. It also includes the territorial sea, seabed, subsoil, insular shelves, and other submarine areas, while the waters around, between, and connecting the islands of the archipelago are treated in the Constitution as part of the internal waters of the Philippines.

In international law, the Philippines is an archipelagic State. This means it is constituted wholly by one or more archipelagos and may draw archipelagic baselines joining appropriate outermost points of the outermost islands and drying reefs, subject to the limits imposed by the law of the sea.

The constitutional description of national territory and the international law system of maritime zones serve different functions. The Constitution declares the national domain and preserves claims of sovereignty and jurisdiction; the law of the sea determines how maritime entitlements are measured, what legal powers exist in each zone, and what rights foreign States retain.

A baseline statute is not itself the source of sovereignty over land territory. It is a legal and cartographic method for measuring maritime zones, and it does not by itself acquire, abandon, enlarge, or diminish territory.

Baselines

Baselines are the starting lines from which the breadth of the territorial sea, contiguous zone, exclusive economic zone, and continental shelf is measured. For an ordinary coastal State, the normal baseline is generally the low-water line along the coast; for an archipelagic State, straight archipelagic baselines may enclose the main archipelago when the required geographic conditions are met.

The Philippines uses archipelagic baselines for the main Philippine archipelago. The Baselines Law, as amended, adjusted these lines to conform to the law of the sea and treated certain outlying areas, including the Kalayaan Island Group and Bajo de Masinloc, as a regime of islands rather than as points within the main archipelagic baseline system.

Archipelagic baselines must connect appropriate outermost points and may not depart appreciably from the general configuration of the archipelago. They must enclose the main islands and an area in which the ratio of water to land falls within the permitted range, and they must not be drawn in a manner that cuts off another State from its territorial sea, exclusive economic zone, or the high seas.

The legal importance of a baseline is practical: it fixes where each maritime zone begins and ends. A claim to an island or other land feature must first be resolved by rules on territorial sovereignty; only then can the maritime zones generated by that feature be determined.

Summary of Maritime Zones

Internal Waters

Internal waters are waters on the landward side of the baseline, such as ports, mouths of rivers, and bays that meet the legal requirements for closure as internal waters. They are assimilated to land territory because the coastal State exercises full sovereignty over them.

In internal waters, the Philippines may regulate navigation, entry, customs, immigration, sanitation, security, fisheries, marine protection, resource use, and criminal jurisdiction subject to applicable treaty obligations and immunities. Foreign vessels do not enjoy a general right of innocent passage through true internal waters.

The constitutional statement that waters around, between, and connecting the islands of the Philippine archipelago form part of the internal waters must be read with the Philippines' acceptance of the archipelagic State regime. As a matter of international law, waters enclosed by archipelagic baselines are archipelagic waters, over which the Philippines has sovereignty but in which navigation rights recognized by the law of the sea must be respected.

This distinction matters because sovereignty can coexist with navigation rights. The presence of innocent passage or archipelagic sea lanes passage does not convert the area into high seas or foreign territory; it merely qualifies the manner in which Philippine sovereignty may be exercised against foreign ships and aircraft.

Archipelagic Waters

Archipelagic waters are the waters enclosed by archipelagic baselines, regardless of their depth or distance from the coast. The archipelagic State has sovereignty over these waters, their airspace, seabed, subsoil, and resources.

The archipelagic State regime preserves the unity of the archipelago. It treats the islands, waters, and other natural features within the baselines as a geographic, economic, and political whole while preserving internationally recognized navigation through and over the archipelago.

Foreign ships enjoy the right of innocent passage through archipelagic waters. Passage is innocent when it is continuous and expeditious and is not prejudicial to the peace, good order, or security of the Philippines.

The Philippines may temporarily suspend innocent passage in specified areas of its archipelagic waters when suspension is essential for the protection of security, provided the suspension is duly published and is not discriminatory. This power is exceptional because ordinary navigation must remain predictable.

Archipelagic sea lanes passage is broader than innocent passage. It covers continuous, expeditious, and unobstructed transit in the normal mode of navigation and overflight through sea lanes and air routes suitable for international navigation between one part of the high seas or an exclusive economic zone and another.

If an archipelagic State designates sea lanes, foreign ships and aircraft must use them for archipelagic sea lanes passage. If no sea lanes are designated, the right may be exercised through routes normally used for international navigation.

Archipelagic sea lanes passage may not be suspended. Ships and aircraft exercising it must proceed without threat or use of force, must refrain from activities other than those incident to normal transit, and must comply with generally accepted international regulations on safety, navigation, and pollution control.

Territorial Sea

The territorial sea is the belt of sea adjacent to the coast or archipelagic waters and extending up to 12 nautical miles from the baselines. The Philippines exercises sovereignty over the territorial sea, including the airspace above it and the seabed and subsoil beneath it.

Sovereignty in the territorial sea includes power to regulate navigation, fisheries, resource use, customs, immigration, sanitation, security, marine scientific activities, environmental protection, and law enforcement. It is broader than the sovereign rights in the exclusive economic zone because it is territorial in character.

The principal limitation on sovereignty in the territorial sea is the right of innocent passage of foreign ships. Passage means navigation through the territorial sea for traversing it without entering internal waters, proceeding to or from internal waters, or calling at a port facility outside internal waters.

Passage must be continuous and expeditious. Stopping and anchoring remain part of passage only when incidental to ordinary navigation, required by force majeure or distress, or necessary to assist persons, ships, or aircraft in danger.

Passage is not innocent when the foreign ship engages in activities prejudicial to the peace, good order, or security of the Philippines. Non-innocent activities include threat or use of force, weapons exercises, intelligence collection, propaganda affecting defense or security, launching or taking on aircraft or military devices, illegal loading or unloading, serious pollution, fishing, research or survey activities, interference with communications, and activities not directly connected with passage.

The Philippines may adopt laws on innocent passage relating to safety of navigation, traffic schemes, protection of navigational aids, cables and pipelines, living resources, fisheries, conservation, pollution prevention, marine scientific research, customs, fiscal, immigration, and sanitary matters. Such laws must not impair the substance of the right of innocent passage.

Foreign submarines and other underwater vehicles must navigate on the surface and show their flag while exercising innocent passage in the territorial sea. This rule reflects the coastal State's security interest in knowing the identity and presence of underwater vessels within its sovereign waters.

Criminal jurisdiction over a foreign ship passing through the territorial sea is ordinarily restrained. It may be exercised when the consequences of the offense extend to the coastal State, when the offense disturbs the peace of the country or good order of the territorial sea, when the ship's master or the flag State's diplomatic or consular officer requests assistance, or when enforcement is necessary to suppress illicit traffic in narcotic drugs or psychotropic substances.

Civil jurisdiction over a foreign ship in passage is also limited. The coastal State should not stop or divert the ship merely to exercise civil jurisdiction over a person on board, although measures may be allowed for obligations or liabilities assumed or incurred by the ship during or for the purpose of its voyage through coastal State waters.

Warships and government ships operated for non-commercial purposes enjoy immunity, but immunity does not authorize disregard of coastal State laws on passage. If a warship fails to comply with lawful regulations and disregards a request for compliance, the Philippines may require it to leave the territorial sea immediately, while the flag State remains internationally responsible for resulting loss or damage.

Contiguous Zone

The contiguous zone is the area adjacent to the territorial sea and may extend up to 24 nautical miles from the baselines. It is not part of the territorial sea, and the coastal State does not exercise full sovereignty over it.

The Philippines may exercise the control necessary in the contiguous zone to prevent infringement of customs, fiscal, immigration, or sanitary laws and regulations within Philippine territory or the territorial sea. It may also punish infringement of those laws and regulations committed within Philippine territory or the territorial sea.

The contiguous zone is therefore an enforcement buffer. It allows action before a vessel reaches the territorial sea or after it leaves, but only for the specific categories of laws recognized by the law of the sea.

The phrase "control necessary" limits the zone. It does not authorize a general police power over all activities at sea, and it does not convert the contiguous zone into national territory.

Protection of archaeological and historical objects found at sea may also justify coastal State control in the contiguous zone. Unauthorized removal of such objects may be treated as a violation connected with the coastal State's protected interests.

Exclusive Economic Zone

The exclusive economic zone is an area beyond and adjacent to the territorial sea, extending up to 200 nautical miles from the baselines. It is neither territorial sea nor high seas in the full traditional sense; it is a special functional zone created by the law of the sea.

In the exclusive economic zone, the Philippines has sovereign rights for the purpose of exploring, exploiting, conserving, and managing natural resources. These rights cover living resources, such as fish, and non-living resources of the waters, seabed, and subsoil, as well as other activities for the economic exploitation and exploration of the zone, such as energy production from water, currents, and winds.

Sovereign rights are exclusive in the sense that if the Philippines does not explore or exploit the resources, no other State may do so without Philippine consent. They are not the same as sovereignty because the zone is not part of Philippine land territory or territorial sea.

The Philippines also has jurisdiction in the exclusive economic zone over artificial islands, installations, and structures; marine scientific research; and protection and preservation of the marine environment. These powers are functional and must be connected with the purposes recognized by the law of the sea.

Artificial islands, installations, and structures in the exclusive economic zone do not possess the status of islands. They do not have their own territorial sea, and their presence does not affect the delimitation of maritime zones.

The Philippines has the exclusive right to authorize, construct, operate, and use artificial islands and certain installations and structures in its exclusive economic zone. It may establish reasonable safety zones around them, subject to international standards and the due regard owed to navigation.

Other States retain freedoms of navigation and overflight in the exclusive economic zone. They may lay submarine cables and pipelines and conduct other internationally lawful uses of the sea related to those freedoms, provided they have due regard to the rights and duties of the Philippines.

The due regard standard works both ways. The Philippines must respect lawful uses by other States in the exclusive economic zone, while other States must respect Philippine sovereign rights over resources and jurisdiction over the environment, research, and installations.

Foreign fishing in the Philippine exclusive economic zone requires Philippine consent. Unauthorized fishing may be met by boarding, inspection, arrest, and judicial proceedings consistent with the law of the sea and domestic legislation.

Marine scientific research in the Philippine exclusive economic zone generally requires Philippine consent. The rule protects the coastal State because research may affect resources, environmental management, security interests, or future resource exploitation.

The exclusive economic zone is central to Philippine rights in the West Philippine Sea. Expansive assertions of historic rights cannot defeat the exclusive economic zone and continental shelf entitlements recognized under the law of the sea when those assertions exceed the maritime zones that land features may lawfully generate.

Continental Shelf

The continental shelf consists of the seabed and subsoil of submarine areas that extend beyond the territorial sea throughout the natural prolongation of the land territory to the outer edge of the continental margin, or to 200 nautical miles from the baselines where the continental margin does not extend that far.

The Philippines has sovereign rights over the continental shelf for the purpose of exploring it and exploiting its natural resources. These rights cover mineral and other non-living resources of the seabed and subsoil, and living organisms belonging to sedentary species.

Continental shelf rights exist automatically. They do not depend on occupation, effective possession, proclamation, or actual exploitation, because they arise from the coastal State's natural prolongation and from the law of the sea.

The continental shelf differs from the exclusive economic zone in subject matter. The exclusive economic zone includes rights in the water column and resources of the waters, while the continental shelf concerns the seabed and subsoil.

Within 200 nautical miles, the exclusive economic zone and continental shelf usually overlap in space but not in legal basis. A single area may therefore involve fisheries jurisdiction in the water column and shelf jurisdiction over petroleum, gas, minerals, and sedentary species below.

The continental shelf may extend beyond 200 nautical miles when the legal and scientific requirements for an extended continental shelf are satisfied. In such a case, the coastal State's rights beyond 200 nautical miles remain limited to the seabed and subsoil; the water column above may remain subject to high seas freedoms.

The Philippine Rise illustrates the difference between shelf rights and territorial sovereignty. Recognition of an extended continental shelf gives the Philippines sovereign rights over seabed and subsoil resources in the recognized area, but it does not make the overlying waters part of Philippine territory or territorial sea.

Other States may navigate, overfly, and lay submarine cables and pipelines above or on the continental shelf, subject to the coastal State's rights over exploration, exploitation, drilling, artificial islands, installations, structures, and environmental protection. The Philippines may not unjustifiably interfere with protected uses, but other States may not impair Philippine shelf rights.

Islands, Rocks, Low-Tide Elevations, and Artificial Islands

Maritime zones are generated by land, not by water. A feature must qualify as land territory above water at high tide before it can generate maritime entitlements of its own.

An island is a naturally formed area of land, surrounded by water, which is above water at high tide. A full island may generate a territorial sea, contiguous zone, exclusive economic zone, and continental shelf.

A rock that cannot sustain human habitation or economic life of its own generates only a territorial sea and contiguous zone. It does not generate an exclusive economic zone or continental shelf.

A low-tide elevation is naturally formed land that is above water at low tide but submerged at high tide. By itself, it does not generate maritime zones when located outside the territorial sea of a mainland or island.

A low-tide elevation within the territorial sea may be relevant as a baseline point if the legal conditions are met. Outside that setting, it cannot be treated as an independent generator of maritime entitlements.

An artificial island is constructed by human activity and has no natural island status. It does not generate a territorial sea, exclusive economic zone, or continental shelf, although the coastal State may regulate and protect it when it is lawfully placed within a zone where the State has jurisdiction.

For outlying Philippine-claimed features treated as a regime of islands, each feature's maritime entitlement depends on its own natural character. The surrounding waters cannot be claimed merely by drawing a broad enclosure around a group if the individual features do not legally generate the claimed zones.

Historic Rights and Maritime Entitlements

Historic title and historic rights must be distinguished from maritime zones under the law of the sea. Historic title is a claim of sovereignty over a maritime area, while lesser historic rights may refer to long-standing use, access, or resource-related practices.

The modern law of the sea leaves limited room for historic claims that are inconsistent with the exclusive economic zone and continental shelf regimes. A State cannot use a generalized historic-rights assertion to defeat another coastal State's legally measured exclusive economic zone or continental shelf.

Traditional fishing practices may be relevant in narrow settings, especially around a territorial sea historically used by fishermen of different nationalities. They do not create a general license to exploit living and non-living resources throughout another State's exclusive economic zone.

In Philippine maritime disputes, the controlling inquiry is not whether a line has been repeatedly drawn on a map, but whether a lawful land feature generates the maritime zone claimed and whether the claimed activity is compatible with the rights of the coastal State.

Delimitation and Overlapping Claims

Maritime zones may overlap when coasts of opposite or adjacent States are close to each other. In that situation, the existence of an entitlement must be distinguished from the delimitation of the boundary.

Entitlement asks whether a State has a legal basis to claim a maritime zone from its land territory. Delimitation asks where the boundary should be drawn when that entitlement overlaps with the entitlement of another State.

Delimitation of the territorial sea ordinarily uses a median line unless historic title or special circumstances justify another result. Delimitation of the exclusive economic zone and continental shelf seeks an equitable solution under international law.

Pending final delimitation, concerned States should pursue provisional arrangements of a practical character and should refrain from acts that would jeopardize or hamper the reaching of a final agreement. Such arrangements do not prejudice the final boundary.

Joint development may be used as a provisional arrangement for resource use in disputed or overlapping maritime areas. It is a practical cooperation device and does not necessarily recognize the other State's sovereignty or concede the final maritime boundary.

Philippine Maritime Zones Act and Domestic Effect

The Philippine Maritime Zones Act identifies and harmonizes the maritime zones of the Philippines with the Constitution, the Baselines Law, and the law of the sea. It gives domestic statutory expression to internal waters, archipelagic waters, the territorial sea, the contiguous zone, the exclusive economic zone, and the continental shelf.

The statute is important because domestic agencies, courts, law enforcement units, fishery regulators, environmental authorities, and resource managers need clear statutory zones for the exercise of public authority. A maritime entitlement is strongest in practice when domestic law, maps, enforcement jurisdiction, and international law speak in the same direction.

The creation or declaration of maritime zones under domestic law does not eliminate the need to comply with international limits. Philippine statutes operate within the framework of the Constitution and the law of the sea, especially where navigation, overflight, foreign vessel immunity, environmental obligations, and overlapping entitlements are involved.

Domestic law may prescribe offenses and enforcement mechanisms for illegal fishing, unauthorized research, marine pollution, customs violations, immigration violations, sanitary violations, and unlawful exploitation of resources. The validity of enforcement at sea depends on matching the offense and enforcement power to the correct maritime zone.

Operational Consequences of Each Zone

The closer the zone is to land territory, the stronger the legal power of the Philippines. Internal waters and the territorial sea involve sovereignty; the contiguous zone involves limited enforcement control; the exclusive economic zone and continental shelf involve sovereign rights and functional jurisdiction.

Sovereignty is the broadest authority and resembles the power exercised over land territory. Sovereign rights are narrower, exclusive, and purpose-based, mainly attached to resources and defined regulatory subjects.

Jurisdiction in the exclusive economic zone does not allow the Philippines to prohibit all foreign military, navigational, or overflight activity merely because the activity occurs within 200 nautical miles. The legal question is whether the activity violates Philippine resource rights, environmental jurisdiction, research control, installation jurisdiction, or other recognized coastal State powers.

Conversely, the freedoms retained by other States do not permit them to fish, drill, construct installations, conduct resource surveys, or exploit seabed resources in Philippine maritime zones without consent when those activities fall within Philippine sovereign rights or jurisdiction.

Airspace follows the character of the maritime zone. The Philippines has sovereignty over the airspace above internal waters, archipelagic waters, and the territorial sea, while foreign aircraft retain overflight freedoms above the exclusive economic zone and high seas, subject to applicable international rules.

The seabed and subsoil also follow zone-specific rules. Beneath internal waters, archipelagic waters, and the territorial sea, Philippine sovereignty applies; in the continental shelf, Philippine authority is framed as sovereign rights over exploration and exploitation rather than full territorial sovereignty.

Correct classification controls enforcement. A fishing vessel in the territorial sea may implicate sovereignty and innocent passage rules, a fishing vessel in the exclusive economic zone implicates sovereign rights over living resources, and a vessel suspected of customs evasion in the contiguous zone implicates only the limited preventive or punitive control recognized for that zone.