The century-old assumption
The assumption was intuitive and fair-sounding: if Party A prevents the fulfilment of a condition precedent to Party A's own obligation, through A's own breach, the law deems the condition satisfied, so Party B can claim the underlying sum as a debt rather than being left to damages. It seemed obvious that you should not be able to escape a debt by sabotaging its trigger.
It drew on the Scottish case Mackay v Dick & Stevenson (1881) 6 App Cas 251, where the House of Lords recognised a deemed-fulfilment principle in Scots law. For generations, English lawyers assumed the same applied here.
King Crude demolished it
In King Crude Carriers SA v Ridgebury November LLC [2025] UKSC 39, a unanimous Supreme Court held there is no deemed fulfilment doctrine in English law. Where a contract makes payment conditional on an event and the event does not occur, the payment obligation never arises - and the fact that the debtor's own breach prevented the event does not change that.
The Court was blunt about the consequence: contract law permits efficient breach, and a defendant may therefore profit from its own wrong. The buyers had agreed to pay deposits within three banking days of the deposit holder confirming the accounts were open; they never provided the documents, the confirmation never came, and so the deposits never became due.
Damages, not debt
The sellers' remedy was damages for breach of contract - whatever loss they could prove flowed from the buyers' failure to provide the documents - not a claim for the deposits as debts. That is a materially weaker position: damages must be proved, mitigated, and are subject to any cap.
The Court rejected attempts to reach a different result through implied terms or strained interpretation. If parties want protection against a contract-breaker relying on non-fulfilment it caused, they must say so expressly. The Court pointed the way: a term can make clear that a condition precedent to a debt does not apply where the debtor's own breach caused the failure.
What it means for milestones and approvals
The reach goes well beyond ship sales. In construction and IT contracts, payment is routinely tied to milestones, deliverables, or acceptance. After King Crude, if the client prevents a milestone - withholding access, refusing approvals, failing to supply information - the contractor cannot claim the milestone payment as a debt. It must claim damages, proving causation and loss and living within any cap that may be far below the milestone sum.
A common example: payment tied to user acceptance testing, where the client repeatedly cancels sessions, fails to provide environments, and assigns no qualified testers. Testing never completes; the payment was conditional on completion; so the payment never falls due. The developer is pushed into a damages claim despite the client's breaches.
Draft an express prevention clause
The fix is explicit. If you want protection, include a clause to the effect that where the other party's material breach is the sole cause of a condition not being met, the payment is deemed due as if the condition had been satisfied, and may be claimed as a debt. Without that, the King Crude default applies and you are left to damages.
In review, this is now a first-order check on any conditional payment: is there a prevention carve-out, and does it sit on the right side? Its absence is exposure you can quantify.
Use at the desk
Practical checklist
- Treat King Crude as the default: prevention of a condition does not make the debt payable (King Crude [2025] UKSC 39).
- Do not rely on a deemed-fulfilment or prevention principle - English law has none.
- For any conditional payment, add an express prevention clause where the other party could block the trigger.
- Draft the prevention clause to deem the condition met (and the sum claimable as a debt) where the other side's material breach was the sole cause.
- Remember the fallback is damages - proved, mitigated, and capped - which may be far less than the sum.
- In review, flag conditional payments with no prevention carve-out as quantifiable exposure.
This guide is informational only and is not legal advice. It does not replace advice from licensed counsel on the facts of a specific transaction.
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