Answer
Flag State Duties (UNCLOS Article 94)A Flag State is the nation under whose laws a ship is registered and whose flag it flies. It has primary jurisdiction and responsibility over the ship, master, officers, and crew in administrative, technical, and social matters.
Core Obligations:
Maintain Ship Register: Must keep a national register recording names and technical particulars of ships flying its flag.
Ensure Seaworthiness & Safety:
Ensure mandatory initial and periodical surveys are conducted by qualified surveyors or Recognized Organizations (ROs, e.g., IRS, ClassNK, DNV).
Enforce compliance with international standards regarding construction, machinery, safety equipment, and navigation (SOLAS).
Safe Manning & Crewing: Ensure the vessel is manned with qualified officers and crew who hold valid STCW certificates and comply with minimum safe manning levels.
Social & Labor Conditions: Enforce living standards, working conditions, and occupational safety on board under the Maritime Labour Convention (MLC, 2006).
Marine Casualty Investigation: Mandated to conduct a formal inquiry into every marine casualty or navigation incident on the high seas involving its ships that results in loss of life, severe injury, or significant environmental damage.
Pollution Prevention: Ensure its ships comply strictly with MARPOL discharge limits and carry valid statutory prevention certificates.
A Coastal State is a nation exercising sovereign rights or jurisdiction over specific maritime zones extending from its baseline: Internal Waters, Territorial Sea (12 NM), Contiguous Zone (24 NM), and Exclusive Economic Zone (EEZ, 200 NM).
Core Obligations & Rights:
Respect Innocent Passage (UNCLOS Article 24): Must not hamper or impair the right of foreign ships to enjoy innocent passage through its territorial sea. It cannot impose requirements that effectively deny passage or discriminate against ships of any state.
Publicity of Navigational Hazards: Must give prompt, clear publicity to any known dangers to navigation within its territorial sea (e.g., uncharted wrecks, shallow waters, damaged aids to navigation).
Environmental Preservation (UNCLOS Part XII): Has the right and duty to adopt non-discriminatory laws to prevent, reduce, and control marine pollution from foreign vessels in its territorial sea and EEZ.
EEZ Resource Management (UNCLOS Article 56): Holds exclusive sovereign rights to explore, exploit, conserve, and manage living (fisheries) and non-living (oil, gas, minerals) resources in its EEZ.
Enforcement Powers: May institute proceedings or require information from foreign vessels in its territorial sea or EEZ suspected of committing severe pollution violations.
A Port State is a nation in whose internal waters or offshore terminals a foreign vessel is voluntarily berthed or anchored. Port State duties act as a crucial regional safety net to catch substandard ships that flag states fail to regulate effectively.
Core Obligations & Rights:
Port State Control (PSC) Inspections: Conduct standardized inspections of foreign vessels to verify that ship condition, certificates, equipment, and crew competence comply with major IMO/ILO conventions (SOLAS, MARPOL, STCW, MLC, Load Line).
Detention Authority (UNCLOS Article 219): If a foreign vessel is found to be non-compliant or unseaworthy such that it threatens safety or the marine environment, the Port State must detain the vessel until deficiencies are rectified before allowing it to sail.
Extraterritorial Pollution Enforcement (UNCLOS Article 218): When a vessel is voluntarily within its port, the Port State can investigate and institute legal proceedings regarding unauthorized MARPOL discharge violations committed outside its own coastal waters (e.g., on the high seas).
Cooperation with Flag States: Transmit inspection reports, casualty data, and evidence of violations to the ship's Flag State Administration. Regional PSC Memorandums of Understanding (MoUs)—such as the Indian Ocean MoU, Paris MoU, and Tokyo MoU—harmonize these inspection procedures globally.