For any maritime business, a sanctions screening programme is only as good as the lists it screens against. A counterparty, a vessel, a beneficial owner or a port operator that sits on the wrong list can freeze a payment, void cover, expose a charterer to enforcement action and put a ship off-hire while lawyers untangle the exposure. The difficulty is that there is no single global list. A shipowner, charterer, broker, bank or marine insurer must screen against several overlapping regimes at once, each maintained by a different authority, each with its own rules about who is caught. This guide explains the main lists a maritime operator should screen against, what a designation actually means, where secondary sanctions risk comes from, and how list changes need to flow into a working screening programme.
Most maritime sanctions exposure traces back to four authorities. You should treat all four as live inputs to screening, not as alternatives.
If your screening covers only one jurisdiction, you have a gap. A US-touching dollar payment, a UK-flagged or UK-insured hull, and an EU port call can each pull a different regime into the same voyage.
A designation is not a warning label. When a person, company or vessel is listed on the SDN List, the UK Sanctions List, the EU consolidated list or the UN Consolidated List, the practical effect is usually an asset freeze and a prohibition on dealing. For US purposes, all property and interests in property of an SDN that are subject to US jurisdiction are blocked, and US persons are generally prohibited from transacting with that party. Under UK and EU asset freezes the effect is comparable: funds and economic resources must be frozen and may not be made available, directly or indirectly, to the designated party.
For ships, OFAC and other authorities can list a vessel itself as blocked property. Designated vessels are identified by their International Maritime Organization (IMO) number, alongside flag, vessel type and year of build, because the IMO number stays with the hull through changes of name, owner and flag. That makes the IMO number the single most reliable screening key for a ship, and the reason name-only vessel screening is unsafe.
The hardest sanctions exposure is the exposure you cannot see on the face of a list. OFAC's 50 Percent Rule holds that any entity owned, directly or indirectly, 50 per cent or more in aggregate by one or more blocked persons is itself treated as blocked, even though it does not appear on the SDN List by name. Ownership aggregates: if two SDNs each hold 25 per cent of a company, the company is caught. It also applies through layers, so a designated owner sitting two or three corporate tiers up still contaminates the subsidiary you are actually dealing with.
OFAC does not publish a list of these majority-owned entities, so the burden falls on the screening party to map beneficial ownership. The UK and EU apply their own ownership-and-control tests with a broadly similar effect. For maritime work this is where most surprises live: the named charterer or port agent is clean, but the holding company, the technical manager or the ultimate beneficial owner is not. Effective screening therefore has to reach beyond the immediate counterparty into the ownership and control structure behind it.
Secondary sanctions extend exposure to non-US parties. Rather than prohibiting US persons from a transaction, they threaten foreign companies and financial institutions with loss of access to the US financial system if they deal with certain sanctioned targets. A non-US owner or charterer with no US nexus can still be exposed if a counterparty, cargo or trade is designated as carrying secondary-sanctions risk. The practical result is a chilling effect well beyond the letter of any single list: banks, insurers and flag registries routinely decline business that is technically lawful for them but carries secondary-sanctions risk. Screening that looks only for primary, name-on-list matches will miss this category of risk entirely.
Sanctions lists are not static reference data. Authorities add, amend and remove designations continuously, and a name added this morning can change the legality of a fixture you signed last week. A screening programme has to treat list changes as a live feed, not a quarterly download. In practice that means:
Sanctions screening fails quietly: a stale list, a name-only vessel check or an unmapped beneficial owner produces a clean result that is wrong. Verihelm is an analyst-verified maritime intelligence platform that brings the regimes above into one screening picture, matching counterparties and vessels against current OFAC, UK, EU and UN designations, working from IMO numbers and entity identifiers rather than names alone, and surfacing the ownership and control structure behind a counterparty so 50 per cent and secondary-sanctions exposure does not stay hidden. Because every flag is checked by an analyst before it reaches you, the platform cuts the false positives that slow a compliance team while making sure real exposure is not missed. See how Dryad Global approaches sanctions and compliance screening for maritime operators.