Decision making and consent

Circumstances that affect the decision-making process continued

If your patient may lack capacity to make the decision

Mental capacity


Capacity is the ability to make a decision. This ability can vary depending on a patient’s condition and how it changes over time, and on the nature of the decision to be made. For this reason, capacity is described as decision-specific and time-specific; so, a person can only have capacity or lack capacity to make a specific decision at a specific time.

Presuming capacity


You must start from the presumption that every adult patient has capacity to make decisions about their treatment and care. You must not assume a patient lacks capacity to make a decision solely because of their age, disability, appearance, behaviour, medical condition (including mental illness), beliefs, their apparent inability to communicate, or because they choose an option that you consider unwise.

Assessing capacity


Assessing capacity is a core clinical skill and doesn’t necessarily require specialist input (eg by a psychiatrist). You should be able to draw reasonable conclusions about your patient’s capacity during your dialogue with them. You should be alert to signs that patients may lack capacity and must give them all reasonable help and support to make a decision.*


See paragraphs 27–30 for ways of Supporting patients’ decision making.


A person has capacity if they can do all the following:

  1. understand information relevant to the decision in question
  2. retain that information
  3. use the information to make their decision
  4. communicate a decision.

If you believe that a patient may lack capacity to make a decision, you must assess their capacity using the test set out in the relevant legislation, taking account of the advice in the relevant guidance. If you find it difficult to judge whether a patient has capacity to make a decision, you should seek support from someone who knows the patient well, for example, another member of the healthcare team or someone close to the patient.*


Available online at Decision making and consent.


In complex cases where you believe you’re unable to make a judgement, you should seek specialist input from psychiatrists, neurologists, speech and language therapists or liaison nurses. You should also seek specialist input if the patient or someone close to them disagrees with your judgement.


If the patient may regain capacity and the decision can be delayed, you must consider this.