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The information on this page represents our best understanding of legislation and case law as laypeople. It is not a substitute for legal advice.

In order to access treatments, you usually need to have capacity to consent to those treatments. You will be assumed to have capacity, unless there is a reason to believe otherwise. Conditions that might impair your ability to consent include:

  • mental health conditions
  • dementia
  • severe learning disabilities
  • brain damage
  • intoxication

However, just because you have one or more of these conditions does not necessarily mean you lack capacity.

Who has capacity?

Outside of England and Wales

The following information discusses the Mental Capacity Act (2005) and Gillick competency, which are specific to England and Wales. Other laws apply elsewhere:

  • In Scotland, this is covered by the Adults with Incapacity (Scotland) Act (2000) and the Age of Legal Capacity (Scotland) Act (1991).
  • In Northern Ireland, the relevant law is the Mental Capacity Act (Northern Ireland) (2016), and Gillick competency has been adopted there as well.

All of these have broadly the same criteria, though there are some differences in the specific wording.

According to the Mental Capacity Act (2005), you have the capacity to consent to a treatment if you can do all of these things:

  • Understand information about the decision you’re making

    If you can understand information about the consequences of deciding to have the treatment, of deciding not to have the treatment, and of failing to make a decision, you meet this criterion.

    You can ask for the information to be given to you in simple language, with visual aids, or in any other way that might make it easier for you to understand, and this does not affect your capacity.

  • Retain that information

    If you can remember what you’ve been told about that treatment, even if it’s only for a short time, you meet this criterion.

  • Use that information to make a decision

    If you can weigh up the pros and cons of consenting to the treatment, you meet this criterion.

  • Communicate your decision

    If you can communicate your consent with any method of communication, such as spoken language, written language, sign language, or gesture, you meet this criterion.

Unless there is significant evidence to show you don’t meet these criteria, you are assumed to have capacity to consent.

The Mental Capacity Act (2005) relates to adults aged 16 and older. However, the standard of Gillick competence means that the same criteria broadly apply to those under the age of 16 1, with the exception that the standard of proof is reversed. In other words, you are not automatically assumed to have capacity, but may have to prove it 2.

What if my doctor determines that I don’t have capacity?

If you’re worried that your capacity to consent might be denied, you could consider bringing an advocate to medical appointments; this could be a friend or relative, or someone experienced in medical advocacy.

If your capacity to consent has been denied and you want to challenge this decision, you can ask for a second opinion, request a “best interest” meeting, or make a complaint:

  • For NHS England, you can complain to PALS
  • For NHS Scotland, you can complain to PASS
  • For NHS Wales, you can find details of your local health board’s process here
  • For HSC Northern Ireland, you can find out how to make a complaint here
  • Private clinics will have their own complaints process


  1. 1.
    House of Lords (1985) “Gillick v West Norfolk and Wisbech Area Health Authority.” Link
  2. 2.
    High Court of Justice, Family Division (2017) “Re S (Child as parent: Adoption: Consent).” Link

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