Captain of the Port Authority

Concept International Law Preferred

Official authority regulating entry, movement and safety of vessels in a port, exercising the port State's powers.

Independent referenceNot an official or legal definition
Sources citedSee the sources at the end of this page
Status Under reviewLast updated 11 October 2026
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Definition

In plain language

The captain of the port is the official in charge of ships in a harbour. This officer decides whether ships may enter and enforces safety and environmental rules.

Academic definition

The coastal State has full sovereignty in its ports as part of its internal waters, and under Article 25(2) UNCLOS it may take steps to prevent any breach of the conditions of admission of ships to internal waters or port facilities. Article 211(3) allows States to set particular requirements for the prevention of pollution as a condition of entry, and Articles 218 and 220 provide for enforcement against violations. The title 'Captain of the Port' is used in some national systems, notably by the United States Coast Guard, while others use harbour master or port authority.

Classification

Term type
Concept
Category
International Law
Subject field
Law of the Sea
Subfield
Port State Authority
Difficulty level
Intermediate
Grammatical category
noun phrase

Language variants

Alternative terms
  • harbour master
  • port captain
  • port authority
Non-preferred terms
  • not_applicable
Abbreviations
  • not_applicable
Acronyms
  • not_applicable
Native terms
  • capitaine de port (French)
Transliteration
not_applicable
Pronunciation
not_applicable

Context

Legal effect: Binding

Scope

Covers the national official or office exercising port jurisdiction; the broader law of port State control and flag State jurisdiction are covered in separate records.

Legal context

UNCLOS Article 25(2), Article 211(3) and Articles 218 to 220; IMO conventions such as SOLAS and MARPOL, enforced through port State control. Ships in port are generally subject to the local State's jurisdiction, except for matters of internal discipline on board.

Diplomatic context

Disputes over detention of ships, denial of port entry for foreign warships or refusals to allow vessels with refugees can become diplomatic issues handled through consulates and flag States.

Institutional context

Exercised by national maritime administrations, coast guards and harbour authorities, in coordination with the IMO's port State control regimes.

Historical context

Harbour masters existed in European ports for centuries, and modern port State control expanded after the Amoco Cadiz disaster of 1978 led to regional memoranda of understanding.

Why it matters

Port authorities can refuse entry, detain unsafe ships and enforce pollution rules, making them a key check on substandard shipping.

Usage

Register: Institutional

Usage note

Titles differ by country, so use 'captain of the port' only when referring to a system, such as the United States, that uses that title.

Example

The captain of the port ordered the tanker to remain at anchor until the safety inspection was completed.

Example scenario

A foreign-flagged ship with unresolved safety defects calls at State A. The captain of the port detains it under port State control rules and allows it to leave only after repairs are certified by the flag State's classification society.

Common misuse

Treating the ship's captain and the captain of the port as the same person; one commands a vessel and the other regulates the port.

Not to be confused with

  • Master of a ship
  • Port state control inspection
  • Flag state jurisdiction

Sources

  1. United Nations Convention on the Law of the Sea (1982), United Nations, Articles 25(2) and 211(3). un.org
  2. Official definition. not_found_in_source
  3. Treaty reference. un.org
  4. Churchill and Lowe, The Law of the Sea. not_found_in_source
  5. not_found_in_source. not_found_in_source

Source type: Treaty. Source reliability: Primary.

This entry is an independent reference definition, not an official or legally binding text. Where an official definition exists, it is linked above and is authoritative. Read our methodology.

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