The price cap is an unusual instrument. Rather than prohibiting a trade, it conditions the availability of the shipping, insurance, brokering and financing services that the trade needs, and it delegates verification to those service providers.
Its enforcement therefore rests on attestations passed along the chain, and the 2023 maritime oil advisory sets out how those attestations are meant to work and what an unreliable one looks like: no itemisation of ancillary costs, refusal to provide underlying documentation, and freight or insurance charges far above market that hide the true price paid.