International Conventions & Flag State

The IMO drafts conventions and, through committees such as the Maritime Safety Committee and the Marine Environment Protection Committee, keeps them current. What it does not do is police them. The IMO has no inspectors, no detention powers and no fining authority — a distinction examiners like to test directly, because candidates who have only half-learned this topic reach instinctively for "the IMO enforces it".

A convention has no legal force over a ship until a state has ratified it and given it effect in that state's own law. That state is the ship's flag state, and once the convention is in force for it, the flag carries the primary duty: surveying its ships, issuing their certificates, and taking action against its own ships that fall short. Because flag-state diligence is not uniform across the world fleet, a second, independent layer exists — port state control. Any port a ship calls at may board and inspect her against the conventions she is supposed to be complying with, and detain her if what is found is dangerous. Port state control enforces the existing rules against a visiting ship; it does not legislate, and it does not replace the flag's own responsibility.

Getting a convention into force is itself a two-stage process worth knowing. First, the convention as a whole needs a minimum spread of ratifying states — enough of them, representing enough of the world's shipping tonnage — before it enters into force at all. After that, the technical annexes of conventions such as SOLAS, MARPOL, the Load Line Convention and the Tonnage Convention are commonly amended by tacit acceptance: an amendment is treated as accepted by every party unless a set number of them formally object within a set period. That is what lets equipment and construction standards keep pace with technology without a fresh multi-year ratification round for every change — the convention stays fixed, but its technical detail can move.

Most of what a ship carries in her certificate folder traces back to one of a small set of parent conventions, and knowing which one governs which subject is the fastest way through this part of the syllabus.

• SOLAS — protects life at sea through construction, stability, fire protection, life-saving and navigational-equipment standards. It is the parent of most of a ship's survey-based safety certificates.
• MARPOL — pollution prevention, split into annexes by source: oil, noxious liquid chemicals in bulk, harmful substances in packaged form, sewage, garbage and air emissions. A ship can be subject to several annexes at once, each with its own survey and certificate.
• STCW — sets training, certification and watchkeeping standards for people, not the ship. A vessel can be perfectly found and still unsafe if her watch is kept by uncertificated or fatigued officers.
• MLC — consolidates seafarer employment and welfare conditions into one instrument, evidenced by a Maritime Labour Certificate and a Declaration of Maritime Labour Compliance, and is itself a routine subject of port state inspection.
• Load Line Convention — sets the minimum freeboard, and so the reserve buoyancy, a ship must carry for her trading condition, marked on the hull and recorded on the Load Line Certificate.
• Tonnage Convention — measures the ship herself, giving gross and net tonnage on one international basis rather than each state's own rules. Many other conventions' thresholds, manning scales and fees are pegged to that single figure.
• COLREGs — governs how vessels behave towards one another to avoid collision. It is not survey- or certificate-driven; it is the universal rule of the road, binding on every vessel regardless of flag.

Notice the pattern: SOLAS and MARPOL are about the ship's condition and operation, STCW and MLC are about the people aboard her, Load Line and Tonnage describe the ship's physical and measured state, and COLREGs governs conduct at sea rather than paperwork. Sorting an exam question into one of those four buckets before answering it removes most of the guesswork.

Every statutory certificate on board is only as good as the survey behind it, and the survey is only as good as the authority that carried it out. Flag states rarely survey every ship themselves; most delegate the technical work to a recognised organisation — typically a classification society — acting under a formal agreement that sets out exactly what has been delegated. The recognised organisation does the surveying and signs the certificate, but the flag state remains legally answerable for what that certificate says. Delegation moves the workload, not the responsibility.

Certificates are not issued once and forgotten. They follow a survey cycle — an initial survey before a certificate is first issued, periodical or intermediate surveys during its life to confirm the ship still meets the standard, and a renewal survey ahead of expiry — with additional surveys required after damage, repair or major conversion. Most statutory certificates run on a period measured in years, with limited, tightly conditioned provision to extend validity for a short period so a ship can reach a port where the renewal survey can actually be done, rather than being forced to sail uncertified or to divert unnecessarily.

That is also why a port state control officer's first move is almost always administrative before it is physical: checking that the certificates on board are in date, match the ship, and were issued by a body the flag state is entitled to delegate to. Only once that paper trail looks sound does the inspection typically move on to condition, and a mismatch or an expired certificate is often enough on its own to trigger a fuller examination.

UNCLOS lays the zones a ship crosses on every coastal passage, and each one carries a different mix of coastal-state and flag-state rights. Getting the boundaries right matters less than getting the character of each zone right.

Within the territorial sea the coastal state holds full sovereignty, moderated only by the right of innocent passage — passage that is continuous and expeditious, and not prejudicial to the coastal state's peace, good order or security. Stopping, loitering, fishing, surveying or exercising with weapons all take a transit outside "innocent" and expose it to the coastal state's full jurisdiction. The contiguous zone, out to 24 nautical miles, adds a narrower coastal-state power: control (not full sovereignty) aimed at preventing and punishing infringement of its customs, fiscal, immigration or sanitary laws.

The exclusive economic zone, out to 200 nautical miles, is where candidates most often slip. The coastal state has sovereign rights there, but they are functional and resource-based — over living and non-living natural resources, and over certain installations and research — not general sovereignty. Freedom of navigation and overflight continue to apply in the EEZ much as they do on the high seas; a ship does not need the coastal state's permission simply to transit it. Beyond 200 miles lie the high seas, where no state holds sovereignty and a ship is, for almost all practical purposes, subject only to the jurisdiction of her flag state.

Three pieces of commercial law sit alongside the safety conventions, and examiners enjoy testing the boundaries between them because the underlying facts can look similar even though the legal consequences are very different.

Salvage rewards a voluntary service, rendered by someone under no pre-existing duty to help, that successfully saves property in danger at sea. No cure, no pay: fail to save the property and, ordinarily, no reward is earned regardless of the effort put in. The reward itself is not a fixed tariff — it is assessed against a set of criteria that weigh the value saved, the danger involved, the skill and effort of the salvor, and the time and expense incurred. Lloyd's Open Form gives owner and salvor a ready-made contract with arbitration built in so terms need not be negotiated in the middle of an emergency, and the SCOPIC supplement sits alongside it to reward environmental protection even in cases where little or no property value is ultimately saved.

General average is a different animal entirely: an intentional, extraordinary sacrifice or expenditure made deliberately, in a moment of peril, for the common safety of the ship, cargo and freight together as one adventure. Because the sacrifice is made for everyone's benefit, everyone who had something at risk shares the cost — not equally, but in proportion to the value each had exposed. The York-Antwerp Rules set out what counts and how it is accounted for, and an average adjuster prepares the statement that turns the principle into a set of figures.

Limitation of liability is a third, separate protection: a shipowner (and certain others in the shipping venture) may cap total exposure to particular classes of claim by constituting a fund related to the ship's tonnage. It is not automatic — the owner must actively invoke it, typically by constituting the fund — and it is not unbreakable: it is lost only where the loss is shown to result from a personal act or omission done with intent to cause it, or recklessly and with knowledge that it would probably result. Ordinary negligence, even serious negligence, does not clear that bar.

Both walkthroughs below run past the point of naming the rule and into applying it — deciding which regime is engaged on the stated facts, then carrying the numbers through to a defensible outcome, the way an examiner will expect it stated.