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Assessing Mental Capacity: A Comprehensive Guide

Updated: Sep 22, 2023

What is Mental Capacity?

Mental Capacity is your ability to make an autonomous decision with the Mental Capacity Act (2005) advising; this should be time and decision specific.

Around two million individuals in England and Wales are estimated to be unable to make decisions for themselves, resulting in approximately six million people, including a wide array of health and social care professionals, plus unpaid caregivers, supporting them.

These health and social care providers have various backgrounds, including Social Workers, doctors, nurses, dentists, psychologists, occupational therapists, speech and language professionals, and more.

Mental capacity can be affected by a stroke or head injury; mental health problems; dementia; learning disabilities; or its treatment; and substance abuse. Consequently, those caring for vulnerable adults must have a good understanding of the Mental Capacity Act (2005), its principles and the assessment of capacity.

Assessing mental capacity is essential to providing healthcare, social care, and financial services in the UK. It is the process of determining whether an individual has the ability to make decisions for themselves. The Mental Capacity Act 2005 (MCA) sets out the legal framework for assessing mental capacity in England and Wales. This blog explores some fundamental considerations regarding legislation and its application to practice.

Decisions are made on micro and macro levels every day; some micro-decisions can include what to wear, what to have for breakfast, whether you need petrol, or whether you will risk it. And we also have those more significant macro decisions. Should we move house? Do I buy a new car? Can I manage my finances? These macro decisions are the decisions we take more time to consider.

Having mental capacity means having the ability to make these micro and macro decisions. For example, we go to a shop and are faced with chocolate at the till and then either decide whether we need chocolate or not as we are trying to be healthy. We can take decision-making for granted, but what if something interrupted our ability to make those decisions, not just macro decisions like investing or buying a house? What if something prevented us from making even micro decisions? For our decision-making to be protected, we have legislation to uphold our decision-making rights.

The Mental Capacity Act 2005

The Mental Capacity Act (2005) is a crucial piece of legislation which protects an individual's right to make decisions. However, it also protects that individual's rights when they cannot make a specific decision. Therefore, according to the Mental Capacity Act (2005), we would adhere to the two-stage test.

We need to adhere to five principles within the Mental Capacity Act (2005); this will ensure that any individual has their rights respected.

Principle 1: A presumption of capacity

Adults must be assumed to be capable of making their own decisions, and that right shall not be infringed upon unless proven otherwise. In other words, it is wrong to assume someone can't make their own decisions due to the presence of a medical condition or disability. Such assumptions are unjustified.

Principle 2: Individuals being supported to make their own decisions

Before determining whether a person cannot make decisions for themselves, all possible efforts should be taken to encourage them and aid them in making their own choices. Even after a lack of capacity has been established, the person must remain actively involved in the decision-making processes. All practicable help should be given in this situation.

This can include providing information in a way that the individual can understand and allowing them to express their views and preferences. Examples include visual aids, interpreters, timelines, decision trees, recognition of body language and adjusting communication. It is also essential to involve the individual's family, friends, and carers in the assessment process, as they may have valuable insights into the individual's ability to make decisions. However, being mindful of this is essential to avoid a family member or loved one biasing the decision.

Principle 3: Unwise decisions

Individuals are entitled to make their own decisions, regardless of whether or not these decisions align with what society believes to be 'wise'. This is because we all have different perspectives, values and beliefs that influence how we approach a particular situation or idea. Therefore, it is essential to recognise this right when assessing an individual's capacity.

As an assessor, you cannot allow your values or beliefs to impact an individual's choice. Of course, everyone makes unwise decisions at some point in their life, but if they understand the risks and consequences of the decision and have still made that decision, it should be respected.

Principle 4: Best interests

When dealing with a person lacking the mental capacity to make decisions, it is essential to always act in their best interests. All actions taken should be for their benefit.

Principle 5: Less restrictive option

When making decisions or taking actions on behalf of someone who may lack the capacity to do so, care should be taken to make sure these decisions or actions don't unduly interfere with the individual's rights and freedoms. Any interventions must be appropriate for the specific circumstances of each case.

Who Can Assess Capacity?

A mental capacity assessment can only be completed by a professional with the proper training and credentials. This type of assessment is historically completed by a GP or Medical professional, However Social Workers are called upon to complete mental capacity assessments on a daily basis and apply a holistic social model to and their assessments. Social Workers have recently become the preferred professional for mental capacity assessments by many legal professionals.

Mental capacity assessments are often used in legal proceedings, such as when someone is being appointed as a deputy or power of attorney. The assessment can also be used in legal decisions, such as when someone is considering creating a new will or transferring a property.

Who can make decisions on behalf of someone who lacks mental capacity?

If you have sufficient capacity, you can make your own decisions. The Mental Capacity Act (2005) protects this right and advises that even if you are making what others feel is an unwise decision; then you are still legally allowed to make the decision.

However, if you lack capacity, someone else may need to decide for you. If you have already created a lasting power of attorney, then your attorney becomes the decision maker; if you do not have a lasting power of attorney in place, then someone such as a doctor, social worker or other professional involved in your care may become the "decision maker" however any decisions made should involve all stakeholders this includes your family and friends. Any decisions should be made in your best interests.

For more complex decisions, the court of protection may appoint a deputy to make decisions either for property and financial affairs or for health and social care decisions on your behalf or make a ruling about a specific decision such as medical treatment.

How to assess mental capacity?

The first step in assessing mental capacity in determining whether the individual has a temporary or permanent impairment of the mind or brain.

An impairment of the mind or brain can include (but is not limited to) conditions such as dementia, brain injury, mental health disorders, and learning disabilities. It is important to note that an impairment does not automatically mean an individual lacks capacity. And as an additional note, the impairment or disturbance to the functioning of the mind or brain can be temporary, for example, short-term illness or being under the influence of substances.

The next step is to assess the individual's ability to make a specific decision. The MCA states that an individual lacks capacity if they cannot make a decision for themselves because of an impairment of the mind or brain. This includes an inability to understand the information relevant to the decision, retain that information, use or weigh that information, or communicate their decision.

It is essential to document the process and outcome when assessing mental capacity. This includes the specific decision being made, the information provided to the individual, and the individual's ability to understand and use that information. It also consists of any assistance provided to the individual in making the decision and any restrictions placed on their freedom. Once it has been determined that the individual lacks capacity, a capacity assessment must be conducted to determine the areas where the individual cannot make decisions. While anyone can complete a mental capacity assessment, it is always preferred that a professional such as a Social Worker complete assessments, especially for more complex cases or decisions.

This assessment should consider the individual's ability to understand, retain, and use or weigh information to make a decision. The assessment should also consider the individual's ability to communicate their decision by talking, using sign language, or other means of communication.

It is important to note that an assessment of mental capacity is not a one-off event; it is an ongoing process that must be regularly reviewed and updated as the individual's circumstances and capacity can change. If an individual lacks capacity, a decision-maker must be appointed to act on their behalf. This can be a family member, friend, or professional such as a solicitor or social worker. The decision-maker must act in the individual's best interest and must follow the principles of the Mental Capacity Act, which include the least restrictive option and involving the individual as much as possible in decision-making.

Assessing mental capacity is a complex process that requires a thorough understanding of the legal framework and the individual's needs. It is essential to involve the individual as much as possible and consider their views and feelings in the decision-making process. Regular assessment reviews must be conducted to ensure that the individual's capacity is being accurately assessed and that the best possible decisions are being made on their behalf. As an assessor, we must also complete the assessment in a therapeutic; this means you and your family should gain some insight into your current care needs and abilities.

Best interests

Difficulties arise when best-interest decisions are made; families can have differing opinions about what is "best" for their loved one, which can conflict with professionals' views. Therefore, it is essential to take a holistic view of the individual, their situation, their family and their needs. Applying systems theory to understand this works in practice as the individual is an integral part of their system, and we can identify all of the micro, Meso, Exo, Macro, and Chronosystems that impact upon the individual (

This can include an individual's cultural, religious or spiritual views and also affect which option is in their best interests. Therefore, a robust and holistic approach to the individual must be considered when best interests decisions occur.

Credit: Lewis Rios

Lasting Powers of Attorney

A lasting power of atorney (LPA) is a legal document that lets you (the 'donor') appoint one or more people (known as 'attorneys') to help you make decisions or to make decisions on your behalf.

A lasting power of attorney gives you more control over what happens if you have an accident or an illness and cannot make your own decisions (you 'lack mental capacity'). (Gov.UK)

As a rule, it is advisable to have a lasting power of attorney (LPA) in place, as then you can appoint somebody you believe would make decisions you would ordinarily have made for yourself if you did have the capacity. LPA's an excellent concept, and as you can choose who you would want to make decisions for you when you lose capacity, you can have discussions with that individual on the types of decisions an attorney can make. Quite often, we come across people who have left the decision to appoint attorneys too late when the individual has already lost capacity, so being prepared and appointing attorneys in advance is advisable.

A Deprivation of Liberties Saefuard or DOls ensures people who cannot consent to their care arrangements in a care home or hospital are protected if those arrangements deprive them of their liberty. Arrangements are assessed to ensure they are necessary and are in the person's best interests. Representation and the right to challenge a deprivation are other safeguards that are part of DoLS. (Scie)

Sometimes, professionals need to decide to deprive a person of their liberties as the alternative would mean risk to the client. This is known as the Deprivation of Liberty Safeguard (DoLS). For example, if an individual is under constant supervision and is not free to leave, for instance, if they are in a care home or supported living and cannot decide on their residency, they are said to be deprived of their liberty.

A DoLS is put in place to ensure that although it is recognised that the individual has restrictions placed on them that this is lawful and proportionate. Although a DoLS is restrictive, the process is robust, and assessments are carried out to ensure there is not a less restrictive option. There are several reasons why an individual may need to be restricted of their liberties and decisions made on their behalf. Examples are when an individual has dementia, and it is unsafe for them to live in their own home; they cannot make that decision effectively, so the decision is made by professionals in their Best Interests.

Capacity and the Court of Protection and COP3

Briefly mentioned earlier was the Court of Protection (CoP), the role of the CoPis to make decisions on financial or welfare matters for people who can't make decisions at the time they need to be made.

Whilst we come across several different decisions that are put before the Court of Protection, the most common decision is whether a property and financial affairs deputy should be appointed.

The Court of Protection can appoint a deputy to make decisions on behalf of individuals who have lost the capacity to do so. Primarily, this format applies to matters regarding finances and property; although it is rare, a deputy can also be appointed for healthcare and personal care decisions.

When completing a mental capacity assessment for the court of protection, this is done by completing a COP3 form and must be conducted by a qualified and registered health or social care professional such as a Social Worker.


There are many complexities in assessing an individual for mental capacity. Firstly, the two-stage test, then the principles have to be applied as discussed above. Finally, all practicable steps are taken to ensure the individual has the support they require to make an effective decision; if they can't, any decisions made on their behalf should be in their best interests.

Any assessments carried out should be therapeutic in nature so the client is involved in an assessment that promotes their strengths and reduces the barriers that can be present in formal assessments.

At Nellie Supports, we pride ourselves on our team's expert knowledge of the Mental Capacity Act (2005) and decision-specific mental capacity assessments, identifying and applying case laws, and ensuring our reports are robust and detailed. If an individual cannot decide for themselves, we ensure that we capture their wishes and views as part of our therapeutic assessment.

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