Innocent passage
Innocent passage is a foundational principle of international maritime law granting ships of all states—including warships and submarines—the right to traverse the territorial sea of a coastal state up to 12 nautical miles from its baseline, without prior permission, insofar as the passage remains continuous, expeditious, and free from acts prejudicial to the coastal state's peace, good order, or security.[1] Codified in Articles 17–32 of the United Nations Convention on the Law of the Sea (UNCLOS), adopted in 1982 and ratified by 169 parties as of 2025, the regime reconciles coastal sovereignty with navigational freedoms vital for global commerce, military mobility, and resource access, evolving from customary practices traced to bilateral treaties and early multilateral efforts like the 1958 Geneva Convention on the Territorial Sea.[1][2][3] Key provisions mandate submarines to navigate surfaced and flying their flag, prohibit non-innocent acts enumerated in Article 19—such as threats of force, weapons exercises, spying, or serious pollution—and empower coastal states to regulate passage via safety-of-navigation laws while allowing temporary, non-discriminatory suspensions in peacetime for security in designated areas, excluding straits used for international navigation.[1][4] Notable characteristics include its applicability to all vessels irrespective of flag, cargo, or propulsion, reinforcing it as a customary norm binding even non-UNCLOS states, though disputes persist over threshold interpretations of "prejudicial" conduct, particularly for warship maneuvers or surveillance that coastal states deem threatening.[4][5] Controversies frequently involve assertions by coastal powers requiring prior notification or authorization for foreign warships—contrary to UNCLOS's no-permission baseline—or claims that routine military transits inherently prejudice security, as evidenced in tensions over freedom-of-navigation operations challenging excessive maritime claims, where empirical enforcement patterns reveal variances between treaty text and state practice.[1][6][7]Legal Definition and Framework
Core Principles
The principle of innocent passage establishes a legal right for ships of all states, coastal or land-locked, to navigate through the territorial sea of another state, provided the passage remains non-prejudicial to the coastal state's peace, good order, or security. This right, codified in Article 17 of the United Nations Convention on the Law of the Sea (UNCLOS, 1982), balances coastal state sovereignty over its territorial sea—extending up to 12 nautical miles from the baseline under Article 3—with the international interest in freedom of navigation.[8][1] The regime applies universally to merchant vessels, warships, and other craft, without discrimination based on flag state, and reflects customary international law predating UNCLOS.[4] Passage itself requires continuity and expeditiousness, meaning vessels must proceed without unnecessary delay through the territorial sea solely for traversing it or to enter/exit internal waters or ports. Article 18 of UNCLOS defines passage as including incidental stops or anchoring only when necessary for ordinary navigation or due to force majeure, such as unavoidable distress.[8] This ensures the right supports efficient transit rather than lingering activities that could encroach on coastal jurisdiction. Submarines and other underwater vehicles must navigate on the surface and show their flag during passage, as stipulated in Article 20, to maintain transparency and mitigate security concerns.[8][1] Innocence hinges on the absence of acts that prejudice coastal interests, per Article 19(1) of UNCLOS, which deems passage non-innocent if it involves threats or use of force against the coastal state's sovereignty, any act aimed at collecting intelligence prejudicial to its defense, propaganda undermining its fundamental policies, weapons exercises, or willful damage to marine environments or facilities.[8][1] Vessels must also conform to generally accepted international regulations for preventing collisions and protecting navigation aids, as outlined in Article 21, reinforcing the principle's emphasis on safe, non-disruptive transit.[8] This framework prioritizes empirical assessment of harm over presumptions, requiring coastal states to base any non-innocence determination on observable prejudicial conduct rather than mere intent or capability.[5]UNCLOS Provisions
The United Nations Convention on the Law of the Sea (UNCLOS), adopted on December 10, 1982, and entering into force on November 16, 1994, establishes the regime of innocent passage in Part II, Section 3 (Articles 17–32).[1] This framework affirms that ships of all states, whether coastal or land-locked, enjoy the right of innocent passage through the territorial sea of a coastal state, defined as the waters adjacent to the baselines up to 12 nautical miles seaward.[1] Innocent passage is characterized as continuous and expeditious navigation through the territorial sea and adjacent archipelagic waters, with stopping or anchoring permitted only if incidental to ordinary navigation or rendered necessary by force majeure or distress.[1] Passage qualifies as innocent provided it remains not prejudicial to the peace, good order, or security of the coastal state, and occurs in conformity with UNCLOS and other international rules.[1] Article 19 enumerates specific acts that render passage non-innocent, including any threat or use of force against the coastal state's sovereignty, any act of propaganda aimed at affecting the coastal state's defense or security, any act of spying or intelligence collection, and activities involving weapons exercises or weapons practice.[1] Additional non-innocent acts encompass willful acts loading or unloading goods, currency, or persons contrary to coastal state laws; acts of serious pollution; fishing activities; research or survey operations; or interference with coastal state communication systems or facilities.[1] Passage by submarines and other underwater vehicles must occur on the surface and with the vessel flying its flag, showing due regard for the coastal state's safety.[1] Coastal states retain authority under Article 21 to adopt laws and regulations relating to innocent passage, covering aspects such as the safety of navigation, protection of navigational aids, conservation of living resources, prevention of infringement on fisheries laws, preservation of the marine environment, prevention of infractions of customs, fiscal, immigration, or sanitary laws, and safeguarding cultural heritage.[1] Such measures must not discriminate among foreign vessels, impair the right of innocent passage, or apply to the design, construction, manning, or equipment of foreign ships unless drawing upon generally accepted international rules or standards.[1] Coastal states may designate or prescribe sea lanes or traffic separation schemes for navigation where necessary to promote safe passage, subject to approval by the competent international organization for straits used in international navigation.[1] Foreign nuclear-powered ships and those carrying nuclear or other inherently dangerous substances must carry documents certifying compliance with international safety standards and take special precautions.[1] Coastal states bear duties to neither impose requirements impairing the right of innocent passage nor discriminate in form or in fact against ships based on their flag, and to give due publicity to any dangers to navigation.[1] They may take necessary steps to protect security, including temporary suspension of innocent passage in specified areas for security reasons, provided it is non-discriminatory, publicized in advance, and applied without discrimination.[1] No charges may be levied on foreign ships for innocent passage except for specific services rendered, such as berthing or waste reception, and vessels in distress are exempt from local charges.[1] Warships enjoy the same right of innocent passage, subject to coastal state requirements for prior notification or innocent passage regulations, though the coastal state may require warships to leave if passage is non-innocent.[1]Historical Evolution
Customary Origins
The roots of innocent passage lie in ancient maritime customs, where coastal polities generally refrained from restricting navigation through adjacent waters, as evidenced by Hellenistic Rhodian Sea Law and Roman jurists like Ulpian and Celsus, who described the sea as naturally open to all for common use.[5] By the medieval period, European maritime codes such as the Laws of Oléron and the Consolato del Mare upheld freedoms of navigation amid emerging claims by city-states like Venice and Genoa over specific seas, though without absolute prohibitions on transit.[3] In the 17th century, Hugo Grotius's Mare Liberum (published 1609) advanced the principle of free seas as res communis, arguing that inhibiting navigation contravened natural law and supporting passage rights even near coasts, countering expansive claims like those of Spain and Portugal under the 1493 Papal Bull Inter Caetera.[5][3] This provoked rebuttals, such as John Selden's Mare Clausum (1635, published 1652), which justified national dominion over adjacent waters, yet failed to halt the doctrinal shift toward balancing sovereignty with transit.[5] Cornelius van Bynkershoek refined the framework in De Dominio Maris (1702), limiting territorial sea to the cannon-shot range—roughly one sea league or three nautical miles—beyond which high seas freedoms prevailed, while permitting passage within that belt provided it remained harmless to coastal interests.[3] Emer de Vattel echoed this in The Law of Nations (1758), endorsing coastal jurisdiction over a narrow maritime belt but qualifying it with a right to innocent transit to avoid unduly encumbering global commerce.[5] Through 18th- and 19th-century state practice—manifest in diplomatic correspondence, naval encounters, and expanding trade routes without widespread interference—the doctrine crystallized as customary international law, defined as continuous navigation not prejudicial to the coastal state's peace, good order, or security, prior to 20th-century codification efforts.[4][3] This acceptance reflected opinio juris among major maritime powers, reconciling territorial claims with navigational necessities amid feudal-to-modern transitions in sea governance.[5]Codification in International Treaties
The principle of innocent passage received its initial comprehensive codification in the Convention on the Territorial Sea and the Contiguous Zone, adopted on April 29, 1958, at the First United Nations Conference on the Law of the Sea in Geneva.[9] Articles 14 through 23 of the convention established the right of ships of all states to exercise innocent passage through the territorial sea of coastal states, provided such passage was "not prejudicial to the peace, good order or security" of the coastal state. This framework delineated continuous and expeditious transit without entering internal waters or stopping except in cases of force majeure, while permitting coastal states to regulate passage through laws on navigation safety, environmental protection, and customs, fiscal, and sanitary measures.[9] The convention entered into force on September 10, 1964, after ratification or accession by 38 states, though its limited adoption—52 parties total—reflected ongoing debates over territorial sea breadth and passage rights.[10] The regime was subsequently refined and expanded in the United Nations Convention on the Law of the Sea (UNCLOS), concluded on December 10, 1982, following the Third United Nations Conference on the Law of the Sea.[1] Part II, Section 3 (Articles 17–32) reaffirms the right of innocent passage in Article 17, defining it in Article 18 as navigation through the territorial sea for traversing that sea without delay, and specifies in Article 19 the acts—such as threats of force, intelligence gathering, or weapons exercises—that render passage non-innocent.[1] Distinct rules apply to submarines and other underwater vehicles, which must navigate on the surface and show due regard for coastal state laws (Article 20), while Articles 21–24 outline coastal state regulatory authority, non-suspension in normal circumstances, and protections for passage through straits used for international navigation.[1] UNCLOS entered into force on November 16, 1994, after ratification by 60 states, and as of 2023, it had 169 parties including the European Union, rendering its provisions reflective of customary international law even for non-parties that recognize the innocent passage doctrine.[1][11] These treaties built on prior unsuccessful codification efforts, such as the 1930 Hague Conference for the Codification of International Law, which failed to produce a binding instrument amid disagreements on territorial sea limits.[5] The 1958 and 1982 instruments thus marked the primary treaty-based consolidation, prioritizing balance between coastal sovereignty and navigational freedoms through explicit definitions and reciprocal obligations.[4]Rights and Obligations During Passage
Rights of Passing Vessels
Under the United Nations Convention on the Law of the Sea (UNCLOS), ships of all states, whether coastal or land-locked, enjoy the right of innocent passage through the territorial sea.[8] This right, codified in Article 17, permits foreign vessels to enter and navigate the coastal state's territorial sea—typically extending up to 12 nautical miles from the baseline—without prior permission, provided the passage remains innocent and adheres to specified conditions.[8] Passage entails continuous and expeditious navigation through the territorial sea, either for traversing without entering internal waters or for proceeding to or from internal waters, roadsteads, or port facilities.[8] Stopping and anchoring are permitted only insofar as incidental to ordinary navigation, rendered necessary by force majeure or distress, or for rendering assistance to persons, ships, or aircraft in danger.[8] This framework balances navigational freedom with coastal state interests, ensuring vessels proceed without undue delay or deviation unless justified by exceptional circumstances. Submarines and other underwater vehicles exercising innocent passage must navigate on the surface and display their flag throughout the territorial sea.[8] This requirement, outlined in Article 20, applies uniformly to military and civilian vessels alike, maintaining visibility and accountability during passage. Warships, as ships under Article 17, share this right without distinction, though their operations must avoid rendering passage non-innocent.[8] Coastal states are prohibited from hampering innocent passage or imposing requirements that deny or impair this right, including discriminatory measures against specific states or cargoes.[8] Article 24 mandates that coastal states publicize any navigational dangers within their territorial sea, facilitating safe exercise of the right. Additionally, no charges may be levied merely for the act of passage; fees are limited to specific services like pilotage or towing, applied without discrimination.[8][8] These protections underscore the passage right as a cornerstone of navigational freedom, subject only to compliance with international standards and non-prejudicial conduct.Acts Rendering Passage Non-Innocent
Passage through the territorial sea is deemed non-innocent under Article 19 of the United Nations Convention on the Law of the Sea (UNCLOS) when it becomes prejudicial to the peace, good order, or security of the coastal state, thereby justifying measures by the coastal state under Article 25 to prevent such passage, including expulsion or arrest of the vessel.[1] This determination hinges on the vessel's conduct during passage, which must otherwise conform to UNCLOS requirements for continuous and expeditious transit incidental to navigation.[1] Article 19(2) specifies that foreign fishing vessels engage in non-innocent passage by conducting fishing activities within the territorial sea, distinct from ordinary navigation.[1] Article 19(3) provides a non-exhaustive list ("inter alia") of activities that render passage non-innocent, focusing on acts that directly threaten coastal state interests rather than routine maritime operations:- Threat or use of force: Any threat or employment of force against the coastal state's sovereignty, territorial integrity, political independence, or in violation of UN Charter principles, such as simulated attacks or provocative maneuvers.[1]
- Weapons exercises: Conducting any exercise or practice with weapons, including firing drills or testing armaments, which could signal hostility or endanger safety.[1]
- Intelligence gathering: Acts aimed at collecting information prejudicial to the coastal state's defense or security, such as unauthorized surveillance or photographing military installations.[1]
- Propaganda activities: Acts of propaganda intended to affect the coastal state's defense or security, beyond mere expression, such as broadcasting subversive messages.[1]
- Aircraft operations: Launching, landing, or taking on board of aircraft, prohibiting overflights or deck operations not incidental to navigation.[1]
- Unauthorized loading or unloading: Loading or unloading of commodities, currency, or persons in contravention of coastal state laws, including smuggling or illegal immigration facilitation.[1]
- Interference with systems: Acts aimed at disrupting the coastal state's communication systems, facilities, or installations, such as jamming signals or cyber intrusions.[1]
- Wilful pollution: Intentional and serious pollution of the marine environment contrary to UNCLOS standards, enabling enforcement beyond standard navigation incidents.[1]
- Fishing: Engaging in fishing activities, reinforcing the specific prohibition for fishing vessels under Article 19(2).[1]
- Research and surveys: Carrying out research or hydrographic survey activities without coastal state consent, often viewed as resource prospecting or mapping threats.[1]
- Resource interference: Acts interfering with the coastal state's sovereign rights over continental shelf, exclusive economic zone, or superjacent resources, such as unauthorized seabed operations.[1]
- Other unrelated activities: Any activity lacking a direct bearing on passage, serving as a catch-all for deviations like prolonged loitering or commercial operations.[1]
Suspension and Coastal State Controls
Conditions for Temporary Suspension
Article 25, paragraph 3, of the United Nations Convention on the Law of the Sea (UNCLOS), adopted on December 10, 1982, and entered into force on November 16, 1994, permits a coastal state to temporarily suspend innocent passage of foreign ships in its territorial sea under strict conditions.[1] The suspension must apply without discrimination in form or in fact among foreign ships, be limited to specified areas rather than the entire territorial sea, and be essential for the protection of the coastal state's security, explicitly including scenarios such as weapons exercises.[1][12] Moreover, such suspension takes effect only after having been duly published, ensuring advance notice to affected states and vessels, typically through nautical charts, notices to mariners, or international notifications.[1] These requirements prevent arbitrary or permanent closures, codifying a balance between coastal sovereignty and the navigational freedoms enshrined in UNCLOS Part II.[1] Non-compliance with these conditions could render a suspension invalid under international law, potentially exposing the coastal state to claims of undue interference with innocent passage rights.[13] In time of war or any other emergency affecting the coastal state's security, Article 25, paragraph 4, authorizes broader protective measures, which may include suspension of innocent passage, though still subject to the non-discriminatory principle implicit in UNCLOS frameworks.[1] Unlike peacetime suspensions, emergency measures under this paragraph do not explicitly mandate prior publication or confinement to specified areas, reflecting the exigencies of heightened threats, but they remain tied to verifiable security imperatives rather than political or economic motives.[1][14] Historical applications, such as temporary exclusions during military maneuvers, underscore that suspensions must be proportionate and temporary to align with customary international law preceding UNCLOS codification.[5]Regulatory Powers of Coastal States
Coastal states hold enumerated regulatory authority over innocent passage in their territorial sea, as codified in Article 21 of the United Nations Convention on the Law of the Sea (UNCLOS), to address specified interests without hampering the fundamental right of passage.[8] This authority permits the adoption of laws and regulations in conformity with UNCLOS and other rules of international law, covering areas such as the safety of navigation and regulation of maritime traffic; protection of navigational aids, facilities, and installations; safeguarding cables and pipelines; conservation of marine living resources; enforcement of fisheries laws; environmental preservation and pollution control; marine scientific research and hydrographic surveys; and compliance with customs, fiscal, immigration, or sanitary regulations.[8] These measures apply to all vessels exercising innocent passage, which requires continuous and expeditious navigation through the territorial sea, typically up to 12 nautical miles from baselines.[8] Such regulations are constrained to prevent overreach: they shall not extend to the design, construction, manning, or equipment of foreign ships unless implementing generally accepted international rules or standards, thereby preserving flag state primacy in those domains.[8] Coastal states must provide due publicity to these laws and regulations, ensuring foreign vessels are informed of applicable requirements.[8] Foreign ships are obligated to comply with these provisions, alongside generally accepted international regulations on collision prevention, such as those in the International Regulations for Preventing Collisions at Sea (COLREGS).[8] Non-compliance may render passage non-innocent under Article 19, justifying coastal state intervention to prevent or terminate such passage.[8] In addition to general regulations, coastal states may designate sea lanes and traffic separation schemes within the territorial sea to enhance navigational safety, particularly requiring tankers, nuclear-powered ships, and those carrying nuclear or inherently dangerous substances to use prescribed routes.[8] Designations must account for recommendations from competent international organizations like the International Maritime Organization (IMO), customary international navigation channels, vessel and channel characteristics, and traffic density, with clear indication on charts and due publicity.[8] For nuclear-powered ships and those with hazardous cargoes, UNCLOS mandates adherence to special precautionary measures and documentation established by international agreements during innocent passage.[8] Broader duties under Article 24 prohibit coastal states from imposing requirements that deny or impair innocent passage or discriminate against ships based on flag state or cargo origin, ensuring regulations serve legitimate interests without practical effect of restriction.[8] Coastal states must also publicize known navigational dangers in the territorial sea.[8] These powers balance coastal sovereignty—extending fully to the territorial sea since the 1982 UNCLOS—with the navigational freedoms essential for global maritime trade, reflecting customary international law principles predating the treaty's entry into force on November 16, 1994.[8]Distinctions from Related Maritime Regimes
Comparison with Transit Passage
Innocent passage applies to the territorial sea, extending up to 12 nautical miles from a coastal state's baseline, granting foreign vessels the right to navigate continuously and expeditiously without prejudicing the coastal state's peace, good order, or security.[1] In contrast, transit passage governs straits used for international navigation, connecting one part of the high seas or exclusive economic zone to another, or leading to territorial seas of two or more states, emphasizing a broader freedom of navigation and overflight for ships and aircraft.[1] This regime, codified in Articles 37–44 of the United Nations Convention on the Law of the Sea (UNCLOS), prioritizes unimpeded transit to preserve global maritime connectivity through chokepoints like the Strait of Hormuz or Malacca Strait.[1] A core distinction lies in navigational freedoms: under innocent passage (UNCLOS Articles 17–26), submarines must surface and fly their flag, while aircraft overflight is prohibited, and activities like weapons exercises or intelligence gathering render passage non-innocent.[1] Transit passage, however, permits submarines to remain submerged in their normal mode of operation and allows continuous overflight, without subjection to innocent passage's prejudiciality criteria, fostering a more permissive environment for military assets.[1][15] Coastal state authority diverges sharply: innocent passage may be temporarily suspended for security reasons (UNCLOS Article 25), and states can regulate aspects like sea lanes or environmental protection (Article 21), potentially requiring prior notification for warships in practice, though UNCLOS does not mandate it universally.[1] Transit passage cannot be suspended or hampered (Article 44), with regulations limited to traffic safety, protection of navigation aids, and environmental safeguards, provided they conform to generally accepted international rules and give due regard to navigation.[1][6]| Aspect | Innocent Passage | Transit Passage |
|---|---|---|
| Geographical Scope | Territorial sea (≤12 nm) | Straits for international navigation |
| Submarine Navigation | Must surface and show flag | May remain submerged |
| Aircraft Rights | No overflight permitted | Continuous overflight allowed |
| Suspension by Coastal State | Temporary suspension possible | No suspension permitted |
| Regulatory Focus | Broader controls (e.g., non-prejudicial acts, potential warship notification) | Limited to safety, environment; due regard to transit |