The Supreme Court has unanimously confirmed that issue estoppel remains a doctrine of narrow application and should not be expanded beyond its established limited scope.

Published: 10 July 2026
Authors: Emma Carr

In its recent judgment in Skatteforvaltningen (The Danish Customs and Tax Administration) v MCML Ltd (previously known as ED&F Man Capital Markets Ltd) the Supreme Court held that SKAT’s present claim should not be struck out on the basis of  issue estoppel, despite earlier proceedings between the parties concerning many of the same tax vouchers.

The judgment provides helpful clarification of when issue estoppel will arise and reinforces the distinctions between issue estoppel, abuse of process and precedent.

Background summary

The 2018 claim

In 2018, SKAT commenced proceedings in the Commercial Court against EDFM (and others) in respect of 420 tax vouchers issued by EDFM (a financial brokerage business) to its clients, which those clients had then used in support of applications to SKAT for refunds of withholding tax.  The claim against EDFM was pleaded in negligent misrepresentation and EDFM was designated as a “Non-Fraud Defendant” in contrast to other “Alleged Fraud Defendants”.

The Commercial Court held that SKAT’s claims were inadmissible under the ‘Revenue Rule’ (a common law rule which says that English courts have no jurisdiction to entertain an action for the direct or indirect enforcement of a penal, revenue, or other public law of a foreign state).  SKAT successfully appealed this decision as against the other Defendants, but chose not to pursue that ground as against EDFM, with the result that the Commercial Court’s finding that the Revenue Rule barred SKAT’s claim against EDFM was final in the 2018 proceedings.

The 2022 claim

In 2022, SKAT issued the present second set of proceedings against EDFM in respect of some of the same tax vouchers and five additional ones.  This time SKAT alleged certain statements in the tax vouchers were fraudulent, as opposed to negligent, misrepresentations.  EDFM applied for strike out and argued that the earlier proceedings gave rise to an issue estoppel and an abuse of process preventing the second claim from proceeding.

At first instance the Commercial Court dismissed that argument as the claims involved different causes of action and different factual allegations, and an examination of the circumstances in which SKAT raised the allegation of fraud revealed no Henderson¹abuse.

EDFM appealed and the Court of Appeal partially upheld the appeal.  It agreed with the Commercial Court that the 2022 claim was not an abuse of process, but found that the 2022 claim was barred by an issue estoppel (albeit with some differences in reasoning) and should therefore be struck out.

SKAT appealed to the Supreme Court.

Supreme Court judgment

The Supreme Court unanimously allowed SKAT’s appeal, such that the 2022 claim should not be struck out.  Giving the leading judgment, Lord Sales and Lord Doherty held that the Court of Appeal had adopted an overly broad approach to identifying the issue said to have been determined in the earlier proceedings.

The Court reaffirmed that issue estoppel is a doctrine of substantive law which operates only in limited circumstances, and highlighted a number of well-established legal principles:

• the issue said to give rise to the estoppel must have been necessary and fundamental to the earlier decision.
• whether the issue arose in the parties’ pleading is an important consideration when assessing whether its determination was necessary and fundamental to the earlier decision.
• only an issue which formed the immediate foundation of the earlier judgment can give rise to an issue estoppel. Wider reasoning of observations made in reaching that decision cannot.
• issue estoppel should remain narrowly confined – the Court emphasised that issue estoppel operates inflexibly and involves a serious interference with the ordinary entitlement of litigants to present their claims and to defend themselves.  For that reason, the doctrine has consistently been applied narrowly. Expanding the doctrine beyond its established limited would risk preventing parties from litigating issues that had never truly been determined between them.
• issue estoppel is distinct from abuse of process – the Court rejected any suggestion that issue estoppel should be expanded to achieve similar outcomes to abuse of process. Unlike issue estoppel, abuse of process provides a flexible framework for regulation of a situation similar to that in the present case, balancing the interests of the parties and seeking to achieve overall justice between them. Giving issue estoppel an expansive interpretation would cut across and significantly displace the rules on abuse of process.
• similarly, the judgment also draws a clear distinction between issue estoppel and the doctrine of precedent. Issue estoppel is concerned with identifying the factual and legal issues that were necessary to the earlier judgment. By contrast precedent concerns identifying legal principles established by a previous decision for application in future cases. Conflating the two doctrines would risk extending issue estoppel beyond its proper limits.

With all this in mind, the Supreme Court concluded that the issues determined in the earlier 2018 proceedings were not the same as those raised in the 2022 claim. Although the 2022 proceedings concerned many of the same tax vouchers, the claims rested on different factual allegations and different causes of action. The earlier 2018 decision did not therefore create an issue estoppel.

Why does this matter?

The decision does not change the law of issue estoppel. Rather it emphasises its narrow scope, helpfully distils the key principles from the authorities, and clarifies the delineation between the three doctrines which may or may not come into play in a similar situation.

For businesses involved in complex commercial disputes, claims frequently evolve as new evidence emerges or different causes of action become available. The judgment confirms that a subsequent claim will not necessarily be barred simply because it arises from the same underlying events. The critical question is whether the specific issue said to found the estoppel was actually determined, was necessary and fundamental to the earlier judgment, and formed the immediate foundation of it.

The judgment also provides useful guidance on the relationship between issues estoppel, abuse of processes and precedent. Parties considering whether earlier proceedings preclude subsequent claims should analyse each doctrine separately rather than assuming the existence of one will determine the application of another.

Key takeaway

This is a relatively concise judgment but one with practical significance for commercial litigants. While it does not change the underlying law, it provides authoritative guidance on identifying issues capable of giving rise to an issue estoppel and confirms that the doctrine remains a narrow one, to be applied within carefully defined limits

Businesses involved in complex litigation should carefully assess whether an earlier judgment truly determined the issue said to found an estoppel before concluding that subsequent proceedings are barred.

¹ Henderson v Henderson (1843) 3 Hare 100)