Marcus v Marcus: what the case means for trust disputes and beneficiary wording

Written by Ryan Taylor, Partner, supported by Emily Thurgood, Solicitor in our Private Wealth Disputes team.

It is not uncommon for trust disputes to arise from difficult family dynamics and breakdowns in relationships. A particularly interesting case, Marcus v Marcus, was heard on appeal in the High Court and highlights the difficulties families, especially children in families with complex parentage, may face when interpreting trust instruments.

The case involved a trust settled by the deceased, Stuart, during his lifetime for the benefit of his “children and remoter issue” (“the Trust”). At the time of his death, Stuart believed he had two children: Jonathan and Edward. However, in a shocking turn of events, it later transpired that their mother had had an affair, and it was discovered that Edward might not have been Stuart’s biological son.

Jonathan brought proceedings to establish the correct interpretation of the Trust on the basis that, if Edward was not Stuart’s biological child, he should not benefit from the Trust. The value of the Trust at the date of the hearing was approximately £14.1m.

In this case, the court considered two important issues:

• Was Edward the biological son of Stuart, the settlor?
• If not, does the term “children of the settlor” in the Trust deed include a son who is not biologically related?

With the help of DNA testing, expert reports and the mother’s witness evidence, the court concluded, on the balance of probabilities, that Edward was not Stuart’s biological son. This set the stage for a much more intricate debate and review of the case law surrounding trusts and the principles of construction. Did Edward still count as a child of the settlor and therefore benefit under the Trust?

Why does biological status matter?

It is generally advisable for settlors to be specific about who they wish to benefit from trust assets. Historically, the law has taken a very literal approach to interpreting classes of beneficiaries and the meaning of collective nouns. For example, step-children are not considered to come under the umbrella of “children” in any trust document. In this context, “children” relate to biological children and adopted children only, as adopted children have the same rights as biological children under statute.

If an individual wishes to benefit their step-children in a will or trust, they should say so and specifically state their relation or, preferably, refer to them by name.

The term “remoter issue” is often seen in wills and trusts and is a traditional way of referring to further lineal descendants, such as grandchildren and great-grandchildren. This is most commonly used when introducing a class of beneficiaries who may not yet be born.

It was therefore important in a case such as Marcus v Marcus to establish whether there was a biological relationship. The easiest way to do this is through DNA testing, as was seen in this case. If there is a biological link, the dispute quickly resolves itself. If not, a more technical interpretation debate begins.

How did this affect the interpretation of the Trust?

In Marcus v Marcus, the court made clear that it would not be appropriate to take a literalist approach to the interpretation of the Trust as would be traditionally expected. Instead, the Trust had to be considered in context.

In particular, the intention of the settlor was relevant and should be taken into account when interpreting the Trust deed. For all intents and purposes, in 2003 when the Trust was set up, Stuart had two sons – Edward and Jonathan. The court at first instance found no reason to suggest that Stuart ever intended for his sons to be treated differently under the Trust, or for one to be excluded.

The Judge at first instance sought to approach the matter objectively, stating that: “the court is concerned to identify the intention of the settlor by reference to what a reasonable person, having all the background knowledge available at the time, would have understood the language in the trust to mean”.

The court found that the evidence overwhelmingly supported a broader interpretation of the meaning of ‘children’, such that Edward was included as a beneficiary in the same way as Jonathan. Specifically, the Judge said: “I consider that the surrounding circumstances point overwhelmingly in favour of a wider meaning than biological child being adopted. A reasonable person…would readily conclude that when using ‘children’ Stuart intended this word to be understood as meaning Edward and Jonathan; and not ‘Edward and Jonathan provided they are in fact my biological sons’”.

Jonathan appealed that decision, and the appeal was heard in June 2025, with judgement handed down on 9 July 2025. The appeal was dismissed and the first instance decision was firmly upheld. The High Court Judge stated that: “the settlement was intended to operate in the real world, and in that real world – Stuart’s real world in particular – Edward was Stuart’s child”.

Both the Judge at first instance and the Judge on appeal made it clear that the correct interpretation depended on the context and the facts as the settlor believed them to be at the time the Trust was created. Stuart believed Edward to be his child and had every intention for him to benefit from the Trust in the same way as any other child of his.

This case aligns the common law approach to the interpretation of trusts with the approach taken in relation to wills. For many years, the court has continuously approached the interpretation of ambiguous wills in light of the testator’s intention and their circumstances at the time of execution. Marcus v Marcus now provides an important authority and sets a precedent for the interpretation of trust instruments that was not there before.

So how important is biological status in will and trust disputes?

Does this judgement undermine the role scientific evidence plays in resolving disputes and the traditional definitions that have long been upheld? On a literal reading of the Trust deed, once it was established that Edward was not Stuart’s biological son, he might have been thought not to benefit from the Trust as he was not a child of the settlor.

DNA testing proved to the court, with a very high probability, that Edward and Jonathan shared only one parent: their mother. However, this evidence proved almost obsolete as the court interpreted the Trust deed by reference to the facts as Stuart, the settlor, believed them to be at the date the Trust was created.

Should we therefore amend our definition of “children” to include ‘those whom any reasonable person would conclude were believed to be the settlor’s children at the time the Trust was created’?

What if Stuart had found out during his lifetime that Edward was not his biological child and had ceased treating him as a child of the family? Perhaps the outcome would have been different. It seems that so long as there is evidence of the settlor’s (or testator’s) intention and beliefs at the time of settlement, whether or not these are strictly true by a scientific standard, then it is likely that a court would interpret the trust in line with those beliefs as if they were fact.

What this case means for trust disputes and does it benefit step-children in your will?

If you are considering making a will or setting up a trust, it is important to be specific about your beneficiaries and/or classes of beneficiaries to ensure there is no ambiguity. Ultimately, the more specific a trust document is, the less room there is for dispute. For example, if you wish to benefit your children but are unlikely to have any more, you may wish to refer to them by name rather than including them within a wider class.

You should also always keep your will and any trusts you have in place under review. A will drafted 10 years ago may no longer reflect your current wishes or family circumstances.

Most importantly, it is always recommended to seek legal advice. Trusts and wills can be complex documents to draft and can give rise to disputes if not drafted correctly. It is always best to seek the assistance of an expert who can advise you on how to reduce the risk of future disputes.