To make a will or a power of attorney, you must have ‘mental capacity’. But what does ‘mental capacity’ mean, and when might you not have it? Let’s take a look.


What is mental capacity?

Mental capacity is the ability to make your own decisions. 

If you don’t have the mental capacity to make a certain decision right now, it means you aren’t able to do one or all of the following:

  • Understand information that relates to the decision
  • Remember that information long enough to make the decision
  • Use the information you’ve been given to come to a conclusion
  • Tell others what your decision is (this could be through non-verbal communication, like squeezing a hand)

When we look at what is meant by ‘mental capacity’, it’s important to remember that:

  • You can have the mental capacity to make some decisions, but not others. For example, you might be perfectly able to decide what you want to wear that day, but not have the mental capacity to choose whether or not to sell your house.
  • You may have mental capacity some of the time, and not other times. For example, you might find it possible to make decisions in the morning, but lose the ability as you become more tired during the day. 
  • You’re assumed to have the mental capacity to make a decision unless it has proven impossible. It’s the job of the people who are looking after you to try to help you make your own decisions as much as possible, during the times you’re most able.


When might you lack mental capacity?

You might lack decision making capacity if you have, for example:

  • Dementia
  • A mental health illness
  • A stroke
  • A brain injury
  • A severe learning disability

Or if you’re unconscious, due to anaesthetic or an accident that has knocked you out.

However, just because you have one of the conditions above doesn’t necessarily mean you don’t have mental capacity. The people who are caring for you must always give you a chance to make a decision for yourself before stepping in. 


Power of attorney and mental capacity

Making a power of attorney is a way to give someone you trust the ability to speak for you if you ever lose the mental capacity to make decisions.

You can choose attorneys (family or friends) who will represent you, and set out guidelines they have to follow as well. It means that you’re more likely to have the treatment and care you want — and your finances can be taken care of, too. 

If you’re worried about losing capacity in the future, a power of attorney is essential. You can find out more about it here.


What is the Mental Capacity Act?

The Mental Capacity Act protects people who can’t make decisions on their own about their treatment and care. It sets out guidelines for how they should be treated by healthcare professionals and carers. The MCA applies to people over the age of 16.


How does the Mental Capacity Act assess capacity?

What does having mental capacity mean under the MCA? The Act sets out a two stage test to check if someone lacks capacity:

  1. Is there something that is affecting how their mind or brain works? This could be an illness, injury or the result of drinking or drugs.
  2. Does it mean that they can’t make a specific decision when the decision needs to be made?

With this test it’s important to remember that mental capacity should be checked for every new decision and every time a decision needs to be made. Just because someone can’t make one decision one specific time, doesn’t mean they can’t make the same decision later or make other decisions.


What does a lack of capacity mean for how you should be treated?

The Mental Capacity Act has guidelines to help those looking after someone who might lack mental capacity. Its aim is to protect vulnerable people and offer a framework that gives them as much freedom and power in their own life as possible. 

The MCA says:

  • Always assume someone is able to make a decision for themselves. Don’t explore alternative options until it’s proven otherwise.
  • Do everything you can to help someone make their own decisions. For example, finding the best way for them to communicate or asking them when they’re best able to reply.
  • Just because someone’s decision isn’t wise, doesn’t mean they lack capacity. You can’t take the decision away from them just because you disagree.
  • If you have to make the decision for them, always act in their best interests. As part of this, you should try to get their opinion and the opinion of the people close to them.
  • Always choose the least restrictive treatment or care option. You should pick the option that has the least impact on their basic rights and freedoms.


Find out more

To find out more about mental capacity and the Mental Capacity Act, check out the NHS guide here.


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