Decisions, dignity, and the law: Understanding mental capacity in divorce

Separation is never easy and can be particularly challenging for both clients and solicitors if there is a question about an individual's capacity. As part of our series of articles for Resolution’s ‘Good Divorce Week 2025’, we consider the issue of mental capacity within family proceedings.  

What is mental capacity? 

Mental capacity is an individual’s ability to understand information related to a decision, make the decision and communicate it to another. It is decision specific. An individual may not have capacity to manage their property and affairs but can have capacity to consent to a marriage or divorce. 

The threshold for determining if an individual has capacity to marry is surprisingly low. The focus is on whether the individual has a broad understanding of the duties and responsibilities which normally attach to a marriage. 

In NB v MI (Capacity to Contract Marriage) [2021] COPLR 207, Mr Justice Mostyn said that living together, loving one another or having sexual relations are not essential features of a marriage when assessing a person’s understanding of what a marriage contract is.

Vulnerable individuals  

Many people get divorced and it can happen at any stage of life. Our clients may sometimes be elderly, victims of domestic abuse, have learning difficulties, have brain injuries, or suffer with serious mental or physical health issues. These characteristics do not necessarily mean that an individual lacks capacity in the context of divorce and family lawyers must be cautious not to presume this.

It is not uncommon for an individual navigating the stress of divorce to make rash and erratic decisions – spending their life savings on a single bet in the casino perhaps. Whilst these choices may raise some eyebrows, such behaviour is not equivocal to a lack of capacity. 

An individual lacks capacity if they are unable to make a decision for themselves “because of an impairment of, or a disturbance in the functioning of, the mind or brain” (Mental Capacity Act 2005; S.2). Although easy to conflate the two, this is not the same as a vulnerable individual.

Litigation capacity 

Family lawyers have a duty to help clients manage the potential long-term financial and emotional consequences of the decisions they make. We must therefore be satisfied that our clients sufficiently comprehend the advice we give to them and can make decisions based on that advice.

Practitioners must make a concerted effort to understand their client’s specific needs, tailor advice and present information in an accessible way. This helps to ensure individuals can digest information in a way which enables them to conduct proceedings safely and independently.

Capacity can fluctuate. Solicitors may be the first to notice changes in their clients’ needs, behaviours or presentation, which may indicate a loss of, or reinstatement in capacity. Our duty to assess capacity is ongoing and is not only relevant at the start of a matter. 

Sometimes, our concern that an individual lacks litigation capacity may persist. In that situation, we have a professional duty to investigate this promptly and make an assessment about next steps. Although raising this with a client can be difficult, it is an important safeguard which ensures we can continue to act in our client’s best interests at the forefront. 

If a matter is in a court timetable, and a determination of capacity is needed, proceedings will need to be adjourned and no further steps can be taken until the court has decided whether an individual in the proceedings has litigation capacity. Any decisions taken before that is established could be rendered void.

Evidence from a medical professional or other third party may be necessary to assist with a capacity assessment. These are conversations which need to be handled sensitively, and in appropriate instances may require engagement with their families or wider support networks too. 

What happens if an individual lacks litigation capacity? 

If it an individual lacks litigation capacity, they become a ‘protected party’. This applies whether the matter is in court proceedings or being managed via other forms of non-court dispute resolution. 

The protected party must appoint a Litigation Friend who will be responsible for making decisions and continuing the proceedings on their behalf. This does not absolve the protected party from involvement with the proceedings, or mean that their wishes should be ignored, and it remains important to ascertain and consider their wishes and feelings wherever possible at all stages of proceedings. 

Acting as a Litigation Friend can be a significant undertaking and careful consideration should be given as to who may be appropriate. It doesn’t have to be a relative or ‘next of kin’ and sometimes this may make things more difficult. Ideally, the individual should have no direct interest in the outcome to the proceedings to avoid any actual or perceived conflict of interest.