Capacity Assessment

How capacity is assessed

As capacity can sometimes change over time, it should be assessed at the time that consent is required by an appropriately person.

Anyone who can have a conversation and form an opinion can conduct a capacity assessment: There is no formal training/qualification required.

Capacity is a bout a particular decision at a point in time: Capacity to make a decision must be done at the time of that decision.

Medical professionals are best placed to assess capacity for healthcare decisions: If the issue is a medical decision then the capacity assessment can be done by the medical professional who is recommending the treatment or investigation, involved in carrying it out.

Solicitors are well and best placed to assess capacity to legal decisions: If the issue is a legal or financial matter then the most appropriate person to assess the capacity is the legal or financial expert making the legal or financial arrangement.

All adults are presumed to have sufficient capacity to decide on their own medical treatment, unless there’s significant evidence to suggest otherwise.

What is capacity?

Capacity means the ability to use and understand information to make a decision, and communicate any decision made.

A person lacks capacity if their mind is impaired or disturbed in some way, which means they’re unable to make a decision at that time.

Examples of how a person’s brain or mind may be impaired include:

Someone with such an impairment is thought to be unable to make a decision if they cannot:

  • understand information about the decision
  • remember that information
  • use that information to make a decision
  • communicate their decision by talking, using sign language or any other means

Changes in capacity

A person’s capacity to consent can change. For example, they may have the capacity to make some decisions but not others, or their capacity may come and go.

In some cases, people can be considered capable of deciding some aspects of their treatment but not others.

For example, a person with severe learning difficulties may be capable of deciding on their day-to-day treatment, but incapable of understanding the complexities of their long-term treatment.

Some people with certain health conditions may have periods when they’re capable and periods when they’re incapable.

For example, a person with schizophrenia may have psychotic episodes when they cannot distinguish between reality and fantasy, during which they may not be capable of making certain decisions.

A person’s capacity can also be temporarily affected by:

  • shock
  • panic
  • extreme tiredness (fatigue)
  • medication

Advance decisions and power of attorney

If a person knows their capacity to consent may be affected in the future, they can choose to draw up a legally binding advance decision, also known as a living will.

This sets out the procedures and treatments that a person refuses to undergo.

You can also choose to formally arrange for someone, often a close family member, to have lasting power of attorney (LPA) if you wish to anticipate your loss of capacity to make important decisions at a later stage.

Someone with LPA can make decisions about your health on your behalf, although you can choose to specify in advance certain treatments you’d like them to refuse.

Reference: Consent to treatment – Assessing capacity – NHS (

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