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Understanding mental capacity: advance decisions

Post date: 10/05/2019 | Time to read article: 2 mins

The information within this article was correct at the time of publishing. Last updated 10/05/2019

Mental capacity is the ability to make a decision. If a person lacks capacity, they have an impairment or disturbance that leaves them unable to make a decision. A patient’s capacity to make decisions about their own care is a fundamental part of matters relating to end of life care


An advance decision (“living will”) can be made if the patient knows that they will want to refuse future medical treatment, but may later lack capacity to make that decision. An advance decision can be made by a person who is over 18 and who has capacity.

Advance decision

A valid and applicable advance decision to refuse treatment must be specific to the treatment in question. It has the same force as a contemporaneous decision. As a medical professional, you must follow an advance decision if it is valid and applies to the decision that needs to be made. If you do not follow an advance decision, you could be charged with committing a crime or civil liability.

A valid and applicable advance decision overrules:

  • the best interests provision, which would otherwise allow healthcare professionals to give treatment they believe is in the individual’s best interests; therefore, you must follow an advance decision, even if you do not believe it is in the patient’s best interests
  • the decision of any personal welfare Lasting Power of Attorney (LPA), made before the advance decision was made
  • the decision of any court-appointed deputy.

The Court of Protection has no power to overrule a valid and applicable advance decision to refuse treatment.

What should it contain?

An advance decision can only be made by a person with capacity and can only be used to refuse treatment in the future; it cannot demand specific treatments. It is the responsibility of the person making the advance decision to make sure the healthcare professionals treating them are aware of any decision that has been made. It is recommended that the individual informs their family and GP. Some people will carry a card or wear a bracelet to alert you to the fact that they have an advance decision.

Artificial nutrition and hydration (ANH) is a recognised form of medical treatment and, therefore, can be refused in an advance decision. However, as with all refusals for life-sustaining treatment, it must satisfy requirements in the advance directive – written, signed and witnessed.

Is the advance decision valid?

An advance decision may be invalid if:

  • the decision was withdrawn while the person had capacity
  • after the advance decision was made, an LPA was appointed and given express authority to make the treatment decisions that were covered by the advance decision
  • the person has done something that clearly goes against the advance decision, which suggests that they have changed their mind.

No individual can make an advance decision to ask for their life to be ended – assisted suicide and voluntary euthanasia remain unlawful.


You should not delay emergency treatment to look for an advance decision if you have no indication that one exists. If there is an indication that one exists, you should assess its validity and applicability to the emergency situation as soon as possible and apply it.

Healthcare professionals are protected from liability if they are not aware of an advance decision, or are not satisfied that an advance decision exists, is valid and is applicable to the particular treatment and the current circumstances.

Conscientious objections

If you disagree in principle with the patient’s right to refuse life-sustaining treatment, you should discuss this with a senior colleague and arrange for the transfer of the management of the patient to a colleague.

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