Mental Capacity & Advance Decisions

The Law says that in order to make an Advance Decision you need to have the Mental Capacity to do so. The person who witnesses your Living Will / Advance Decision is, in addition to witnessing that it is you who are signing the document, is also saying that you have the mental capacity to make such a decision.


What is Mental Capacity?

Mental Capacity & Advance Decisions

Mental capacity is defined as the ability to make a particular decision for yourself. By law, in order to be defined as having mental capacity, a person must be able to do the following:

  1. Understand information provided to them to make a decision.
  2. Retain the information given long enough to make the decision.
  3. Use or weigh up that information to make the decision.
  4. Communicate their decision.
Mental capacity is defined as the ability to make a particular decision for yourself.
The 5 Key principles of the act are (according to the Ministry of Justice)

1. Every adult has the right to make his or her own decisions and must be assumed to have capacity to make them unless it is proved otherwise.

2. A person must be given all practicable help before anyone treats them as not being able to make their own decisions.

3. Just because an individual makes what might be seen as an unwise decision, they should not be treated as lacking capacity to make that decision.

4. Anything done or any decision made on behalf of a person who lacks capacity must be done in their best interests.

5. Anything done for or on behalf of a person who lacks capacity should be the least restrictive of their basic rights and freedoms.

The Mental Capacity Act was brought in to provide protection to those adults who do not have the capacity to make their own decisions. It also introduced more structured guidelines and requirements with regards to Living Wills. The new rules relate primarily to an individual’s wish not to receive life saving treatment. Current position Present day laws offer a great deal of protection to those people who either cannot make their own decisions or cannot communicate them. They empower people to be able to record, at any time, what they would want in the future if something should happen to them. If recorded in the correct legal format, that of a Living Will, these wishes cannot be ignored or overruled. This means that you get the treatment you want, can refuse the treatment you don’t want and the burden is not passed onto your loved ones or the medical professionals that are treating you, who will only make clinical decisions.


The Code of Practice to the Mental Capacity Act 2005 that tries to explain the Act in words that are easy to understand. The section dealing with Advance Decisions is at Chapter 9 of the Code (pg 158). Please click here should you wish to see read this.