Coastal state jurisdiction is the jurisdiction enjoyed by the coastal state in relation to breaches of regulations and laws by foreign flagged ships that take place within its jurisdictional zones. The prescriptive and enforcement jurisdiction comprise the main power of a coastal state. Prescriptive is the jurisdiction to prescribe laws and regulations, while Enforcement is the jurisdiction to enforce such laws.

The rights and obligations of states in relation to navigation and pollution are determined primarily by international conventions and customary international law. The United Nations 1982 Law of the Sea Convention (UNCLOS) is the most widely ratified convention in this field of law, outlining the rights and obligations of states in relation to their jurisdictional zones as well as with respect to environmental protection.

The Customary International Law

The Customary International Law is one of the main sources of International Law, involving the principle of custom. Article 38(1) (b) of the International Court of Justice Statute defines customary international law as an "evidence of a general practice accepted as law". This is generally determined through two factors: Firstly, the general practice of states (the objective element) and secondly, the opinio juris i.e. what states have accepted as law (subjective element).

The North Sea Continental Shelf  Cases confirmed that both the state practice the objective element) and the opinio juris (the subjective element), are essential pre-requisites for the formation of a customary law rule. 

Exclusive Economic Zone (EEZ)

a.       Prescriptive rights

It is worth mentioning the fact that the Exclusive Economic Zone (EEZ) did not exist before UNCLOS, where it was a part of the high sea. According to article 55 UNCLOS, the exclusive economic zone is an area beyond and adjacent to the territorial sea, which "shall not extend beyond 200 nautical miles fom the baselines, from which the breadth of the territorial sea is measured" (Art 57). All states enjoy several freedoms in the EEZ including freedom of navigation in the same way as in the high seas (Art 58(1)). However, exercising such freedoms they shall have due regard to the rights and duties of the coastal state and shall comply, pursuant to article 58(3), with the laws and regulations adopted by the coastal state. Article 56 (1) (b) (iii) gives to the coastal state the prescriptive jurisdiction with regard to the protection and preservation of the marine environment. However, this prescriptive jurisdiction is restricted by the article 211 (5), which refers that the laws and regulation adopted have to conform and give effect to generally accepted International rules and standards which have been established by the International Maritime Organisation (a competent international organization). 

b.       Enforcement right

The EEZ is perhaps the most complex of the maritime zones with respect to maritime enforcement. This because of the unique but limited sovereign rights and jurisdiction a coastal state possesses over this area.

Article 73 defines the enforcement jurisdiction (boarding, inspection, arrest and judicial proceedings) of a coastal state relating to its rights under article 58, and specifically the sovereign rights to explore, exploit, conserve and manage living sources.

According to article 220 (3) the coastal state where there are clear grounds for believing that the foreign vessel navigating in EEZ has committed in EEZ or in the territorial sea of a costal state a violation of any applicable international standards, the coastal state may ask the vessel to provide information. Such information includes the ship's identity, port of registry, last and next port of call and other relevant information relevant to establishing the existence of the violation. According to article 220(5), where there are clear grounds that it has taken place substantial discharge, causing or threatening significant pollution, the coastal state can physically inspect the vessel if the required information is not provided or where it is evident that it is not true. Furthermore, if where there is clear objective evidence that a ship has committed a violation of international standards that has resulted in a discharge which caused major damage or threat of major damage to the coastal state the coastal state can institute proceedings and detain the vessel is needed as per article 220(6).

It is noticeable to say that the coastal state will decide what 'clear ground' is. The IMO has also guidance and standards regarding what 'clear ground' is. However, if there is a dispute whether the action of a state to stop a vessel or ask for information is in violation with the UNNCLOS' provisions, then the Arbitration on dispute resolution under UNCLOS between the states will resolve the issue.

c.        Customary international Law

There is not Customary International Law, since this is a new area, which was not pre-exist the UNCLOS. The 200 nautical mile exclusive economic zone was formally developed and adopted for first time in 1982 and before that this area was a part of the high sea. Therefore, no one can make statement regarding what it was enforceable and what it was not before UNCLOS.

However, one other can argue that as early as 1984 a Chamber of the International Court held in Case Concerning Delimitation of the Maritime Boundary in the Gulf of Maine Area (Canada/United States), [1984], para. 94 that the concept of the exclusive economic zone (EEZ) was customary international law. Similarly, in the 1985 Libya v Malta case, the court held that Article 57 is customary international law (par 34). Also, the International court in its decision on merit in Nicaragua case  stated the high seas freedoms of navigation apply in the EEZ, citing article 58 UNCLOS.

In addition, one other can argue that as per the Lotus Case  (paras 46-47), within its territory, a state may exercise its jurisdiction, on any matter, even if there is no specific rule of international law permitting it to do so, however, it cannot exercise its power in any form outside its territory, unless, an international treaty or customary law permits it to do so (para. 45).

Last but not least, the coastal state does not have plenary regulatory and enforcement powers in the EEZ and their actions must be based upon these rights attributed in article 56 subject also to article 59. This point was emphasised in M/V Saiga (No2), where the ITLOS (INTERNATIONAL TRIBUNAL FOR THE LAW OF THE SEA) rejected the attempt by Guinea to apply its customs laws to the EEZ as being contrary to the Convention. This case highlights that the enforcement within the EEZ is subject to general principles on the use of force and related relevant provisions found in the Convention.


a)       Prescriptive rights

The port as a part of the internal waters is exclusively under the coastal state sovereignty. This means that the coastal state has absolute (maximum) jurisdiction and can prescribe its own national legislation, imposing measures. Furthermore, article 211(3) UNCLOS, provides that states may establish particular requirements (e.g National CDEM Standrds) for the prevention, reduction, and control of pollution of the marine environment as a condition for the entry of foreign vessels into their ports or internal waters, however, providing publicity to such requirements and communicate them to the competent international organization, such as the International Maritime Organization (New Zealand case). Regarding the CDEM Standards applied in ports, additional to article 211(3), articles 25(2) and 219 are relevant to the port state's competence to prescribe and enforce CDEM standards to foreign vessels in ports. In addition, following the reasoning of article 220, it follows that it is acceptable that the coastal state is entitled to prescribe national rules and laws as well as applicable international law in relation to pollution prevention.

b)      Enforcement right

Under article 219 UNCLOS, a state can take "administrative measures to prevent the vessel from sailing" in reaction to the violations of seaworthiness within the port, providing for the detention of the vessel prior to its being authorized to proceed to the nearest appropriate yard. Also, according to article 220(2) UNCLOS, a costal state may undertake physical inspection of the vessel, when there are clear grounds that a vessel navigating in the territorial sea of a state, has during its passage violated laws and regulations of that state (national law), and where the evidence so warrants can include the detention of the vessel. Additionally, paragraph 3 of article 220 includes violation of international rules (IMO rules and standards) in the EEZ and in that scenario the coastal state may require the vessel to give information regarding its identity and port of registry. Thus, the coastal state has the right to enforce its national rules and laws as well as applicable international law in relation to pollution prevention under article 220. Moreover, article 226(1c) UNCLOS mentions that during the investigation of a foreign vessel, when a release of a vessel it would present an unreasonable threat of the damage to the environment may the costal state refuse it and detain the vessel. Furthermore, the state can enforce the CDEM standards to foreign vessels in ports from articles 211(3), 25(2) and 219.

Apart from UNCLOS, regulation 8 of Annex V and article 5(2) MARPOL provides that the port state during its inspection on the foreign vessel, when there is a clear grounds that the vessel is not substantial compliance with the Convention, has the right to detain it in the port.

Furthermore, except for article 220 (enforcement rights by a coastal state), under article 218 (1), the port state can have enforcement rights over a vessel which is voluntarily within its port in respect of any discharge from that vessel outside of its jurisdiction and after the request by that State, or the flag state or a state damages or threatened by the discharge violation, or unless this violations have caused or is likely to cause pollution in the jurisdictional zones of the state instituting the proceedings (paragraph 2 ). Additionally, paragraph 3 states that the state of which into its ports there is voluntarily a vessel, shall comply with requests from any state, for investigation of discharge violation refers to paragraph 1, which believed to have occurred in or causes or threatened damage to its jurisdictional zones. This request can also be requested by the flag state, irrespective of the location of the occurred violation.

c)       Customary International law

Under customary international law the coastal state has sovereign rights over its ports and internal waters. It is on the basis of this sovereignty that it regulates access to its ports. The Barcelona Traction Case, suggests that there is a right to exercise jurisdiction on ships voluntarily entering the ports of a state.

There is no right of entry into ports of foreign states in customary International law, reasoning from the Nicaragua  case (i.e the coastal state is not under any obligation to permit access its port). However, for humanitarian and safety reasons, it is generally recognised that any foreign vessel in distress or when there is a human life at stake, this vessel has a right of entry to any foreign port under Customary International Law (e.g. The Nicaragua  case para 123, Creole case 1853The Carlo-Alberto case 1832, The Eleanor Case 1808). In the Nicaragua case, was held that a state can deny the entrance of a foreign vessel to its port.

In addition, despite the fact that the Law of the Sea Convention (LOSC) is silent as to whether foreign ships have a right of access to a port, however, there is a general principle that a state does not have unlimited power to prohibit access to its port. In Saudi-Arabia v Aramco arbitration, the arbitrator observed that: according to a great principle of public international law, the ports of every state must be open to foreign merchant vessels and can only be closed when the vital interests of the state so require. Also, in the Nicaragua case the ICJ also referred to certain rights linked to the freedom of communications and maritime commerce conferring a right of free access enjoyed by foreign ships to ports.

Moreover, a state has the generally recognised right to decide which of its ports are to be open to international maritime commerce. This right of port nomination to the coastal state has been well established in state practice in cases Newcastle v Trinmouth and Attorney General v Bates [1610]. It is also generally accepted that under certain circumstances states are entitle to close ports which are normally open to international traffic. The right of closure for national security is well established. However, the state has the duty to give notice of closure, otherwise the state is responsible for any damage caused by the inefficient notice of the closure (The Martini case).

In the New Zealand case held that it was an essential feature of the freedom of the high seas and the freedom of navigation that the state of nationality of a ship (the flag state) had exclusive jurisdiction over the ship when it was on the high seas. In addition, under the rules of international law a port state had no general power to unilaterally impose its own requirements on foreign ships relating to their construction, their safety and other equipment and their crewing if the requirements were to have effect on the high seas. Any requirements could not go beyond those generally accepted, especially in the maritime conventions and regulations.

Last but not least, the right of innocent passage does not extend to general navigation within the internal waters. Nevertheless, foreign ships which are sovereign immune enjoy the privilege whilst within internal waters (Argentina v. Ghana Case and The schooner Exchange case).

Internal Waters

a)       Prescriptive rights 

In the internal waters the coastal state has absolute jurisdiction and sovereignty and thus, there is not a right of innocent passage. Therefore, the coastal state can prescribe its own national legislation, imposing measures regarding the entry of a ship. Internal waters are defined in article 8 of UNCLOS and the port is a part of the internal waters. Thus, a state can deny or restrict access to its ports to foreign vessels, impose conditions for access and uses its port, impose fines on a ship its port, and detain the ships.

b)      Enforcement rights

Article 220 (1) states that a vessel voluntarily within a port may be subject to proceeding arising from pollution incident which took place in the coastal state's territorial sea (220(2) violation of national law) or EEZ (violation of international rules i.e IMO rules and standards). 

c)       Customary International Law

As internal waters fall within the sovereign territory of coastal state (Nicaragua case) the state has recognised sovereignty over those waters fully encompassing prescriptive and enforcement jurisdiction, subject only to the limitation imposed by national law. A coastal state possesses absolute sovereignty over their internal waters. In the Nicaragua  case, was held that the state can deny the entrance of a foreign vessels to its port.

Also, the right of innocent passage does not extend to general navigation within the internal waters. Nevertheless, foreign ships which are sovereign immune enjoy the privilege whilst within internal waters (Argentina v. Ghana Case and The schooner Exchlines consistent with article 7).

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.