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The Esbern Snare: An overview of maritime zones and use of force against maritime piracy

The Esbern Snare: An overview of maritime zones and use of force against maritime piracy

The Danish frigate, The Esbern Snare, deployed to protect shipping in the Gulf of Guinea was reported to have killed four pirates in waters south of Nigeria in November, 2021. This news was received with a measure of concern in Nigeria. Questions were raised with respect to the possible infringement of Nigeria’s sovereignty and the legality of the force used.

This article proffers an overview of the delineation of maritime zones, and the use of force against maritime piracy, under international law of the sea. The expectation is that it will furnish perspective on some of the matters arising.

Maritime zones

The zones of maritime boundaries are drawn in concentric limits using what the United Nations Convention on Law of the Sea (UNCLOS) calls ‘baselines’. The baseline is the starting point for measuring the limit of a maritime zone. The normal baseline is the low-water line along the coast as marked on large scale charts officially recognised by the coastal state.

UNCLOS divides marine waters into seven zones as follows:

1. Internal waters: Internal waters are those waters that lie landward of the baselines from which the territorial sea is measured. All the water on the coast stopping at the baselines, embracing ports and harbours. Every state enjoys full sovereignty over its internal waters.

2. Territorial sea: The territorial sea is the coastal water of a state not exceeding 12 nautical miles (m) from its baselines. It comprises the seabed and its subsoil, adjacent waters, and its airspace. The coastal states have sovereignty over their territorial sea subject to the right of innocent passage for foreign vessels.

For the passage to be ‘innocent’ it must be continuous and expeditious and must not be prejudicial to the peace, good order or security of the coastal state. The right to transit passage applies to straits used for international navigation. Note that there is no right of innocent passage for aircraft flying through the airspace of the territorial sea.

3. Contiguous zone: Coastal states may assert a contiguous zone not exceeding 24m from its baselines. In this zone, a coastal state may exercise control necessary to punish and prevent infringement of its customs, fiscal, immigration, and sanitary regulations within its territorial sea. Unlike the territorial sea, the coastal state jurisdiction over the contiguous zone does not extend to the airspace.

4. Exclusive economic zone: Coastal states may claim an Exclusive Economic Zone (EEZ), beyond and adjacent to the territorial sea, not exceeding 200m from its baselines. In this zone, the coastal state exclusive jurisdiction is restricted to exploitation, and exploration of resources (living and non-living things) found superjacent to the seabed and its subsoil (limitation ratione materiae). The jurisdiction also extends to the production of energy from the water, currents and winds. Foreign state enjoy the freedom of navigation and over-flight in the EEZ.

5. Continental shelf: There are 2 methods for determining the continental shelf – (i) a distance not exceeding 200m from its baseline (ii) submarine areas extending beyond its territorial sea to the outer edge of the continental margin where the continental edge extends beyond 200m. A coastal state jurisdiction over the continental shelf is confined to explorations and exploitation of mineral and non-living resources of the seabed and subsoil including sedentary species.

6. The high sea: The high sea is the water superjacent to all part of the sea not included in the internal waters, territorial sea and EEZ of a state. UNCLOS provides for the freedom of the high seas. The state which has granted a vessel rights to sail under its flag, has exclusive jurisdiction over that vessel in the high sea.

7. The area: The Area is the common heritage of mankind. It is the seabed and ocean floor and subsoil thereof beyond the limit of national jurisdiction. Activities in the Area are regulated by the International Seabed Authority. The 1994 Implementation Agreement incorporated the concerns of industrialized countries in the original regime of the seabed under UNCLOS.

Use of force against maritime piracy

Some writers agree that the definition of a pirate, under UNCLOS, has a number of conjunctive main elements as follows – (a) illegal acts of violence, detention, or depredation (b) private ends (c) involvement of two ships (d) location on the high sea or outside the jurisdiction of a state. Nigeria has an anti-piracy law – Suppression of Piracy and other Marine Offences Act 2019, which comprises similar elements in defining piracy.

1. Illegal acts of violence, detention or depredation: Some experts believe this element includes not only ‘acts’ per se but the threat of it as well. This view is said to be supported by judicial decisions and inclusion of the wording ‘attempted acts of piracy’ in the International Maritime Organisation (IMO) Code of Practice in the investigation of piracy.

However I would disagree that ‘a threat’ of acts of piracy is synonymous with ‘an attempt’ of acts of piracy. It is possible to argue that a pirate ship stationary or even sailing aimlessly on the high of sea without more can qualify as ‘a threat’ of acts of piracy but without having made any ‘attempts’ of acts of piracy. A scenario where a group of persons arm themselves with guns and head out to sea in a boat with the intention of committing acts of piracy but while out at sea change their minds and decide to head back to shore peacefully, do their mere presence on a pirate-infested route without more qualify as an ‘attempts of acts of piracy’ in law?

2. Involvement of two ships: The illegal acts of violence must be directed from a ship against another ship. The Nigerian Act extends the offence of piracy to acts against a fixed or floating platform. Crew seizure, mutiny, or overpowering of crew during voyage by passengers is not piracy. Though this would fall under marine offences in the SPOMO Act and the SUA Convention.

3. Private ends: Based on this element, foreign warships cannot be regarded as pirates. Acts of violence for political reasons are also excluded.

4. High sea: UNCLOS limits the offence of piracy to acts occurring on the high sea or a place outside the jurisdiction of any state. The SPOMO Act applies to the internal and territorial waters of Nigeria and on international waters. Some writers agree that acts of violence committed in the EEZ also qualify as piracy by virtue of Article 58(2) UNCLOS.

Use of force:

A pirate is an outlaw, an enemy of all mankind (hostes humanis generis), ‘whom any nation may in the interest of all capture and punish’. UNCLOS doesn’t have explicit provisions on the parameters of the use of force in combating pirates found at sea nonetheless seizing a pirate ship implies the use of force.

The UN Basic Principles on the Use of Force and Firearms by Law Enforcement Officials provides that whenever the lawful use of force and firearms is unavoidable, law enforcement officials shall exercise restraint in such use and act in proportion to the seriousness of the offence and the legitimate object to be achieved.

Cases decided by international judicial bodies indicate that the use of force in maritime law enforcement by sovereigns, should be reasonable, proportionate and be as a last resort.

As regards private maritime security contractors, some jurisdictions have issued guidance on the use of force by these outfits against piracy. There have been guidelines by the IMO and publications by other maritime organisations as regards the use of force on board merchant ships – which all uphold the principles of reasonability, proportionality, and necessity.

Read also: ‘Maritime sector has suffered neglect despite its ability to stimulate the economy’


The obligation on state to seize, arrest and punish pirates is discretionary. Most developed states after arresting pirates are reluctant to prosecute them in their own courts due to complexities in criminal proceedings and expenses involved, and to some extent the human rights considerations and possibility of asylum after the pirates have served their sentence with respect to the principle of non-refoulement.

The UN Office on Drug and Crime refers to the Gulf of Guinea as the ‘world’s piracy hotspot’. The International Chamber of Commerce’s International Maritime Bureau (IMB)’s annual piracy report for 2021, while kidnappings at sea dropped 55% in 2021, the Gulf of Guinea continues to account for all kidnapping incidents globally, with 57 crew taken in seven separate incidents.

Most of the pirates in the Gulf of Guinea target oil carrying ship with the motive of stealing oil rather than taking crew for ransom. The negative ripple effects of the activities of these pirates to Nigeria’s blue economy is incalculable. The dire situation has led to an increased presence of international naval vessels to curb piracy on the Gulf of Guinea. The Esbern Snare was one of such vessels.

There are still open questions with respect to the reported incident. The location is given as 25-30m south of Nigeria’s territorial waters. Is this south of Nigeria’s territorial sea or EEZ?

What can be deduced, provisionally, is that the incident did not happen within Nigeria’s territorial sea. UNCLOS allows the combating of piracy in a coastal state’s EEZ subject to the respect for the rights and sovereignty of the coastal state.

The expectation is that if this incident happened within Nigeria’s EEZ, the Danish frigate should have made an attempt to contact the Nigerian Navy before or after the incident in view of the obligation imposed on states performing duties in the EEZ to have due regard to the rights and duties of the coastal state.

The statement by the Danish military was that the Danish frigate spotted a fast-moving vessel carrying eight suspected pirates near a number of commercial ships.

The motorboat, spotted by a helicopter deployed by the frigate, was carrying equipment associated with piracy, including ladders. After the frigate fired warning shots, the pirates opened fire on Danish navy Special Forces, who in turn shot and killed four pirates and wounded one.

The implication here is that the use of force was in self-defense, as a last resort. However, sufficient facts were not provided to conclusively contend that there was reasonable ground for suspecting the occupants of the motorboat to be pirates.

Nigeria has a number of insurgent groups in its restive coastal oil producing communities whose members engage in unlawful acts on the sea for political motives, even fishermen carry arms in these areas for protection. Can the mere act of being ‘fast-moving near commercial ships’ without more be regarded as acts or even attempted acts of violence?

The principle of proportionality also raises the question whether the use of force by the Danish Special Forces was proportionate to the ‘fire’ ‘opened’ by the pirates. Self-defense will not avail an actor whose defensive measures were unreasonably excessive, or disproportionate to the actual threat.

The efforts to suppress piracy on the Gulf of Guinea by international collaboration is commendable. There is some sense that there is no one size fits all approach in applying the principles guiding the use of force at sea.

Each case will be decided on its peculiar circumstances. The incident also reinforces the need for increased synergy between the coastal states in the Gulf of Guinea and the flag states of the international warships providing security in that region, especially in respect of information sharing and prosecution of pirates.

There is need for further clarity from relevant institutions on the duty of flag states capturing pirates, as the practice of releasing pirates to sail ashore is counter-productive to the fight against maritime piracy.

Nwadike, a managing counsel at Pristine and Sage Attorneys, writes from Abuja