Mental capacity is the ability in law to make decisions for yourself.

According to the Mental Capacity Act 2005, mental incapacity exists when ‘a person lacks capacity in relation to a matter if at the material time he is unable to make a decision for himself in relation to the matter because of an impairment of, or disturbance in the functioning of the mind, or brain’.

If an injured party lacks the capacity or ability to manage their own affairs they are known as a ‘protected party’ and will be safeguarded by the Court of Protection.

Adults who lose capacity may have made a Lasting Power of Attorney (LPA) or Enduring Power of Attorney (EPA) in which case this will need to be registered with the Court of Protection so that their chosen attorneys can act on their behalf.

If no power of attorney exists and someone has already lost capacity, a deputy will need to be appointed to take responsibility for the financial affairs of the person. The Court of Protection has to approve the choice of deputy.

Capacity and serious brain injuries

Capacity is particularly relevant in the more serious brain injury cases when the person involved may not be in the position to pursue a claim for compensation themselves and instead have to rely on someone claiming on their behalf, or similarly when a significant award has been made and they will depend on other people to manage the settlement in their best interests to provide ongoing care.

Find a Court of Protection specialist here.


You can see five key principles of the Mental Capacity Act here:

Mental Capacity Act - the key principles (643.4 KiB)

Read about the role of a deputy here:

Mental Capacity Act - the role of Deputy (837.3 KiB)

How do you define an unwise decision?

Mental capacity | defining an unwise decision (830.5 KiB)


How can the Brain Injury Group help you?

If you’ve been affected by brain injury and need free legal or welfare advice, there are several ways to get in touch:

  1. Call us on 0800 612 9660 or 03303 112541
  2. Email us at
  3. Complete this short enquiry form and we’ll get back to you