Supreme Court reshapes the law on issue estoppel

Issue estoppel has long been an established doctrine in English civil procedure. In Skatteforvaltningen v MCML Ltd [2026] UKSC 19, however, the Supreme Court has significantly limited its application, holding that the doctrine must be kept within "narrow limits which are appropriate for a doctrine having such an effect."

This judgment confirms that issue estoppel only arises in respect of issues that were “necessary and fundamental” to an earlier decision, and does not extend to the court's wider reasoning, statements of law or issues inferred from an earlier judgment.

The decision is likely to affect commercial litigation and limit circumstances where defendants can rely on earlier judgments as a means of barring subsequent claims.

Factual Background

In 2018, the Danish Customs and Tax Administration ("SKAT") commenced proceedings against more than 100 defendants, including MCML Ltd (previously known as ED&F Man Capital Markets Ltd) ("MCML"), claiming that MCML had negligently made false representations in tax vouchers submitted in support of refund applications.

A preliminary issue arose as to whether those claims were barred by the foreign revenue rule. The Commercial Court held that they did fall foul of the foreign revenue rule and dismissed the claims against MCML ("Revenue Rule Judgment").

In 2022, SKAT brought fresh proceedings against MCML. In these new proceedings, the claim alleged fraud rather than negligent misrepresentation. MCML argued that the new proceedings were barred by issue estoppel because the Revenue Rule Judgment had already determined the relevant issue. 

The High Court rejected this argument, but the Court of Appeal, by a majority, held that issue estoppel prevented SKAT from proceeding with its new claim.

SKAT appealed the decision of Court of Appeal to the Supreme Court, which was heard on 11 and 12 February 2026.

Supreme Court Decision

On 1 July 2026, the Supreme Court handed down judgment, allowing SKAT's appeal. Giving the judgment of the Court, Lord Sales and Lord Doherty undertook the assessment of issue estoppel and restricted the circumstances in which it can apply.

Issue estoppel – a narrow doctrine

The Court emphasised that issue estoppel has "powerful effect". Once established, it prevents a party from litigating an issue and vindicating what is otherwise a good assertion of their rights. Because of this, the Court held that the doctrine should be confined within "narrow limits".

In those circumstances, the courts should rely upon the more flexible doctrine of abuse of process where fairness requires control of successive rounds of litigation.

The judgment treats issue estoppel as a doctrine that should not be extended to pure points of law, or what merely formed part of the judge's reasoning, and should instead be tethered to the application of the law to the facts before the Court.

As a result, only issues necessary and fundamental to the earlier decision can create an estoppel.

The Supreme Court referred to case law such as Concha v Concha (1886) 11 App Cas 541, Outram v Morewood (1803) 3 East 346, 102 ER 630, New Brunswick Railway Co v British and French Trust Corporation Ltd [1939] AC 1 and Blair v Curran (1939) 62 CLR 464 to come to the conclusion that: "While the immediate foundation of the ultimate decision can give rise to an issue estoppel, elements of the prior court's reasoning leading up to that decision cannot."

Pleadings are key 

Another takeaway from the Supreme Court's judgment is its emphasis on pleadings.

 The Court confirmed that identifying the scope of any issue estoppel requires close consideration of the issues raised on the pleadings in the earlier proceedings. The question before the Court is not what could have been decided, or what follows logically from the judgment, but what issues the parties were actually required to consider.

Whether an issue is "traversable" from earlier proceedings is the key to determining whether an estoppel arises. The Court therefore rejected any attempt to identify issue estoppel through inferences drawn from the earlier judgment.

Different allegations

The 2018 proceedings alleged negligent misrepresentation whilst the 2022 proceedings alleged fraud. Although both proceedings related to many of the same tax vouchers, the Court held that they were not the same issue. The earlier proceedings did not require a determination of whether fraudulent misrepresentations had been made.

Issue estoppel cannot be expanded by inference

The Supreme Court held that parties cannot expand the scope of an earlier judgment by arguing that, had different facts been before the earlier court, the judge would inevitably have reached the same conclusion.

The Supreme Court explained that this is precisely what Duchess of Kingston's Case (1776) 2 Smith’s LC 644 is authority for rejecting.

The value of precedent

Issue estoppel has a stronger precluding effect than the doctrine of precedent. Whilst precedent allows parties to distinguish an earlier decision or invite a higher court to depart from it, issue estoppel prevents the same parties from re-litigating an issue already determined between them. The Supreme Court asserted that extending issue estoppel beyond issues actually decided would risk undermining the doctrine of precedent.

Our View

This decision is significant for the doctrine of issue estoppel and we expect to see shifts in commercial litigation strategy going forward. Broad propositions from earlier judgments can no longer be relied upon. Litigants will need to demonstrate that the issue in question was both pleaded and necessarily determined in the previous decision.

As a result, where a later claim differs even slightly, litigants are likely to rely more on Henderson v Henderson (1843) 3 Hare 100 to assert abuse of process rather than issue estoppel.

How Rosenblatt Can Help

The authors of this article, Luther Kisanga (Partner) and Nadine Clayton (Associate) acted for the Respondent, MCML Ltd in Supreme Court appeal, together with Anthony Field(Joint Managing Partner), Charlotte Woodward (Legal Director), Joelle Bisimwa (Associate) and Josh Field (Trainee Solicitor).

Should you wish to discuss how this decision may apply to you, please get in contact with Luther Kisanga.