Capacity to marry – setting the threshold of understanding

The recent case of Mundell v Name 1, 2019 EWCOP 50 has again highlighted the issue of what a person needs to understand to have capacity to marry. In this particular case ‘P’, a 28 year old gentleman with a diagnosis of learning disabilities, wished to marry his fiancé whom he had met 3 years earlier. The gentleman in question had previously been deemed to lack capacity to manage his property and financial affairs (est. to be £1.5 million). As such he had been appointed a deputy under the Court of Protection. P had previously been deemed to have testamentary capacity.

P’s deputy had concerns about the proposed marriage and noted P’s privately expressed indecision about going ahead with it. This was in addition to a clinician’s assessment that P is easily persuaded, has difficulty saying no, is very vulnerable and would be open to being exploited. P’s deputy also expressed concern that P did not properly understand that, if he married and subsequently divorced, his wife would have a financial remedy claim against his estate.

The judgement

Mostyn J noted that P had already been considered to have capacity to make a will. Furthermore that the threshold of understanding for testamentary capacity is likely to be ‘higher than that is needed validly to contract a marriage’, (see also the ruling of Re DMM 2017). Mostyn J also agreed with Parker J’s judgment in Southwark v KA (2016), which gives effect to the argument that people can have capacity to marry without needing to understand how financial remedy law works.

The threshold of understanding

The threshold of understanding is what a person needs to understand to make a specific decision. It is this that makes capacity item specific. We know that setting the threshold too high prevents too many people from being able to self-determine but setting it too low has the opposite effect.

We are beginning to see a move away from the idea that all decisions can be separated out and seen in isolation. Capacity to marry is one of these.

For a while now, capacity to marry has been seen as being inseparable from capacity to engage in sexual relationships and the ruling of Re DMM (2017) reaffirmed the threshold of understanding to marry as

  • Capacity to engage in sexual relationships.
  • The ability to understand a concept of and the necessity of one’s own consent is fundamental to having capacity: in other words that P knows that they have a choice and can refuse.
  • The ability to understand the nature of the marriage contract.
  • The duties and responsibilities attached to marriage.
  • The contract of marriage was a simple one which did not require a high degree of intelligence to understand.

Setting the threshold

This latest ruling by Mostyn J, reaffirms that the threshold of understanding for capacity to marry is necessarily low. This will be at odds with where many individuals feel the threshold of understanding should be for this particular decision.

The issue is what are, or should be, the foreseeable consequences of getting married. In other words, what do we expect the average person ‘on the Clapham omnibus’ to be able to understand, retain weigh up and use when getting married? Would we expect a person to be able to consider the financial implications of getting married and to what extent would they consider this?

What does social media have to do with capacity to marry?

Whilst there can be no doubt that every decision has some ‘core essentials’ which everyone must be able to understand, in the rulings of Re A (Capacity: Social Media and Internet Use: Best Interests) and Re B (Capacity: Social Media: Care and Contact) Cobb J noted that some elements of the threshold of understanding for the same decision actually varied depending on the specific situation.

An argument could well be made for the same in relation to capacity to marry. For example, one could argue that you would expect the average person with a very limited or modest estate to give scant regard to the financial implications of marriage. Whereas you could argue you would expect the average person with a large estate to give greater weight to the financial implications of marriage.

What seems particularly prudent in this case is the context of the assets. Specifically they were the result of a personal injury claim and therefore the large extent of his assets are protected for his care. Potentially therefore any possible future claim from his wife’s claim would in fact be minimal. This seems to be one of the key comments from the judge and would appear to highlight the importance of considering the reasonably foreseeable circumstances and specifics of the estate.


Disagreements around whether an individual has capacity or not are often centred around a lack of agreement regarding the threshold of understanding. Whilst this most recent case attempts to further clarify the threshold, it seems that there is still someway to go before there is accepted clarity over the core elements that determine the threshold of understanding to marry.

TSF Consultants are recognised as experts in the assessment of mental capacity. We have developed a unique process of setting the threshold of understanding that has been upheld repeatedly in court. If you or your client are looking to have a mental capacity assessment carried out please contact the team on 0333 577 7020 or email us at

About the author: Tim Farmer is the founder of TSF Consultants and a multi-award winning expert and author specialising in the assessment of mental capacity.