Definition of disability - What disability means by law

Definition of disability

The law (Equality Act 2010) sets out when someone is considered to have a disability and is protected from disability discrimination.

What's automatically classed as a disability

People with these conditions and impairments are automatically protected under disability discrimination law:

  • cancer
  • an HIV infection
  • multiple sclerosis (MS)
  • a visual impairment – if someone is certified as blind, severely sight impaired, sight impaired or partially sighted

Progressive conditions

A progressive condition gets worse over time. Examples include Alzheimer's disease, motor neurone disease, muscular dystrophy and Parkinson's.

Someone with a progressive condition is considered by law to have a disability as soon as it starts to have an effect on their normal day-to-day activities, as long as this is likely to be long-term. The effect does not have to be substantial as long as it's likely to become substantial in the future.

The main definition of disability

The law says someone is disabled if both of these apply:

  • they have a 'physical or mental impairment'
  • the impairment 'has a substantial and long-term adverse effect on their ability to carry out normal day-to-day activities'

People with progressive conditions, and conditions or impairments that are automatically classed as a disability, are also protected by law.

What these terms mean

Someone has an 'impairment' if any of their physical or mental abilities are reduced in some way. It could be because of an illness or medical condition but it does not have to be.

A 'substantial adverse effect' means more than just a minor impact on someone's life or how they can do certain things. This may fluctuate or change and may not happen all the time.

'Long-term' means either:

  • it will affect them or is likely to affect them for at least 12 months
  • it's likely to last for the rest of their life

It can still be considered long-term if the effects come and go. For example, a fluctuating condition might affect someone for a few months at a time with other times when they're not affected.

'Normal day-to-day activities' include things people do in their home and social life. It also includes things that let people participate fully in their working life.

For example:

  • communicating with other people
  • driving
  • filling in forms
  • following instructions
  • getting washed and dressed
  • going to the shops
  • preparing and eating food
  • sitting down or standing up
  • using a computer
  • writing

Past disability

The Equality Act 2010 also protects people who are no longer disabled but had a disability in the past.

Other conditions or impairments

It's not possible to give an exhaustive list of all conditions or impairments that might be classed as a disability. In most situations, it's best to look at how someone's condition or impairment affects them, rather than what the condition or impairment is.

However, these are some examples people often ask about.


Severe disfigurement will usually be considered by law to have a substantial adverse effect on someone's ability to carry out normal day-to-day activities. This means that severe disfigurement is usually considered to be a disability.

The law says that there is no need for someone with a severe disfigurement to show the effect their disfigurement has on them.

Other less severe disfigurements to someone's face or body might not have a substantial effect on someone's day-to-day activities so might not be considered a disability.

Long covid

Long covid is still a new illness and it may take time to understand it fully. It can affect a person's day-to-day activities and it's currently understood that it can last or come and go for several months, even years. The effects of long covid could also cause other impairments.

Find out more about whether long covid is treated as a disability


For some people, the menopause can cause severe physical or mental health symptoms that have a long-term and substantial adverse effect on carrying out normal day-to-day activities.

For example, someone could experience severe depression over a number of years because of the menopause and this could affect their ability to work. This could be considered a disability under discrimination law.

Find out more about the menopause and work

Neurodiversity including ADHD, autism, dyslexia and dyspraxia

Attention deficit hyperactivity disorder (ADHD), autism, dyslexia and dyspraxia are forms of neurodivergence – there are others too.

Being neurodivergent will often amount to a disability under the Equality Act 2010, even if the person does not consider themselves to be disabled.

Find out more about neurodiversity at work

Get more advice and support

For more detailed guidance on the definition of disability, read Equality Act 2010 guidance on GOV.UK.

If you have any questions about what disability means by law, you can contact the Acas helpline.

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