by Kate Russell

What is a disability?


A person will be considered to be disabled within the meaning of the legislation if:

  • He has a physical or mental impairment
  • The impairment has a substantial and long-term adverse effect on his ability to perform normal day-to-day activities

If they satisfy these requirements, most conditions are capable of being disabilities.

Some conditions are deemed to be a disability from the date of diagnosis. These include cancer, HIV and MS. Conditions such as severe visual or hearing impairment and facial scarring (other than those caused by the individual, for example, the removal of tattoos) are also likely to be disabilities. As a general rule if you’re not sure it’s best to err on the side of caution and treat a condition as a disability.

Someone who is no longer disabled, but who met the requirements of the definition in the past, will still be covered by the Act. Also protected would be someone who continues to experience debilitating effects as a result of treatment for a past disability.

Meaning of ‘impairment’

In order to fall within the definition of disabled, a person must have a physical or mental impairment. In many cases, there will be no dispute about the existence of an impairment and any disagreement is more likely to be about whether the effects of the impairment are sufficient to fall within the definition. Even so, it may sometimes be necessary to decide whether a person has an impairment so as to be able to deal with issues about its effects.

Impairment is interpreted very broadly and includes damage, defect, disorder or disease.

Whether a person is disabled for the purposes of the act is generally determined by reference to the effect that the impairment has on that person’s ability to carry out normal day-to-day activities.

Some examples of impairments

A disability can arise from a wide range of impairments:

  • Sensory impairments, such as those affecting sight or hearing
  • Impairments with fluctuating or recurring effects, such as rheumatoid arthritis, myalgic encephalitis (ME)/chronic fatigue syndrome (CFS), fibromyalgia, depression and epilepsy
  • Progressive, such as motor neurone disease, muscular dystrophy, forms of dementia and lupus (SLE)
  • Organ specific, including respiratory conditions, such as asthma, and cardiovascular diseases, including thrombosis, stroke and heart disease
  • Developmental, such as autistic spectrum disorders (ASD), dyslexia and dyspraxia
  • Learning difficulties
  • Mental health conditions and mental illnesses, such as depression, schizophrenia, eating disorders, bipolar affective disorders, obsessive compulsive disorders, as well as personality disorders and some self-harming behaviour
  • Produced by injury to the body or brain
  • Club foot
  • Back injury (soft back tissue)
  • Photosensitive epilepsy
  • Cerebral palsy
  • Multiple sclerosis
  • Diabetes
  • Migrainous neuralgia.


According to OECD figures almost 27% of the adult population in the UK is clinically obese and this is likely to increase. Obesity can be a debilitating condition that is associated with an increased risk of a host of diseases. In terms of the workplace, it can also reduce an employee’s ability to carry out work effectively. But is obesity in itself a disability?

In Walker v SITA Information Networking Computing Ltd [2013], the Employment Appeal Tribunal (EAT) ruled that obesity in itself was not a disability under this definition. But it did consider that an obese person may be more likely to come under the definition. For example, diabetes, depression and joint-pain - all associated with and potentially compounded by obesity - may be chronic impairments that have a substantial effect on an individual’s everyday life.

Mr Walker had 16 medical conditions compounded by obesity, but with no single recognisable cause. The EAT found that the test for disability was not necessarily about causes, but primarily about whether or not there was an impairment and the nature of that impairment. On that basis, the court concluded that Mr Walker was disabled under the definition.

The judge remarked that: “Though I do not accept that obesity renders a person disabled of itself, it may make it more likely that someone is disabled.”

The current position is that obesity as a condition in itself does not satisfy the definition of disability, but can offer evidence to allow a court to more readily to conclude that the individual before them does indeed suffer from an impairment. This seems artificial: obesity-related impairments are inherently linked to the obesity, obesity cannot satisfy the definition in itself. As a result, obese individuals are offered only indirect protection on the basis of the extent to which their weight is causing them health issues.


It may not always be possible to categorise a condition as either a physical or a mental impairment. The underlying cause of the impairment may be hard to establish and there may be adverse effects which are both physical and mental in nature. Furthermore, effects of a mainly physical nature may stem from an underlying mental impairment, and vice versa.

Causation of an impairment isn’t relevant, even if the cause is a consequence of a condition which is excluded. For example, liver disease as a result of alcohol dependency would count as an impairment, although alcoholism itself is expressly excluded from the scope of the definition of disability. What it is important to consider is the effect of the impairment, provided that it is not an excluded condition.

More than one medical condition

In some cases an employee may have two or more medical conditions, making it difficult to identify whether he is or is not disabled within the meaning of the law.


B was employed as a mechanical and electrical co-ordinator. His job required him to travel extensively by car. In November 2003, after a long day’s driving, B was so tired he stopped at a service area for a rest. Afterwards, he set off for home and exposed himself to two different groups of women, later admitting that his head was full of ‘weird thoughts and emotions’ at the time. He was subsequently convicted of indecent exposure and dangerous driving. The following day he attended a meeting at work, broke down and was later admitted to hospital for treatment. B was diagnosed as suffering from a moderately severe depressive illness.

B was advised by his solicitors that he did not have to disclose his convictions for indecent exposure to his employer. As a result, he told his employers that he was banned from driving and when questioned why police had quizzed him about a different matter he lied.

Eventually he told his employers the truth and was dismissed on the basis that he had misled them and his conduct could potentially bring the company into disrepute, as there was a risk that it might be repeated in the future.

B brought a successful claim for discrimination based on his mental impairment. The court found that his employer had treated him less favourably because of his condition on the basis that had he not been suffering from the mental illness he would not have committed the offences.

The employer successfully appealed. The Employment Appeals Tribunal stated that it was clear that the sole reason for B’s dismissal related to his exhibitionism, a condition that did not amount to an impairment and that his dismissal did not relate to his depression, which is a qualifying impairment. The depression was underlying to an excluded condition (in this case the exhibitionism), that resulted in less favourable treatment. Therefore his disability (the depression) was not a reason for the less favourable treatment.

It is therefore important to distinguish between an impairment that is regarded as a disability within the meaning of the DDA 1995 and an impairment that underlies an excluded condition under the 1996 Regulations. Therefore, for example, a tendency to steal (or to exhibitionism, or to the physical or sexual abuse of others), is excluded from being treated as a disability and therefore potentially justifies less favourable treatment.

Mental illness

A mental illness does not have to be clinically well recognised to qualify as a disability. However, anyone who has an impairment, including one resulting from a mental illness, will still need to meet the requirements of the definition as set out above, in order to demonstrate that they have a disability under the act.

‘General learning difficulties’ can amount to a disability for the purposes of the DDA, if they have an adverse effect on the employee’s ability to carry out normal day-to-day activities. There is no absolute requirement that evidence of a disability must be provided by a doctor.


D was employed by AW Ltd as a fork-lift truck driver in September 2002. He was dismissed in December 2002. He complained that their dismissal and failure to make reasonable adjustments amounted to disability discrimination.

AW Ltd argued D did not have a mental illness amounting to ‘a mental impairment’ and that they had done all they could, but that he was unable to do his job in a safe manner and he was therefore dismissed.

The court ruled that it was not necessary to establish a specific mental impairment or clinical condition for a person to suffer from a mental impairment within the act and the case was remitted back to the employment tribunal to consider whether D’s impairment had a substantial and adverse effect on his day-to-day activities.

Conditions which will automatically be disabilities

A person with the following conditions is deemed to meet the definition of disabled from the date of diagnosis:

  • A person who has cancer, HIV infection or multiple sclerosis (MS)
  • A person who is certified as blind or partially sighted by a consultant ophthalmologist, or is registered as such with a local authority.

Severe disfigurements, such as visible skin disease, scars and birthmarks, limb or postural deformation, will usually be regarded as a disability. Not all disfigurements will be considered severe. Whether or not they are severe may depend partly on where they are on the body. For example, a birthmark on the back may not be a severe disfigurement, whereas a similar mark on the employee’s face might be considered severe.

Disfigurements which consist of a tattoo (which has not been removed), non-medical body piercing, or something attached through such piercing, are not regarded as a disability.

Excluded conditions

Certain conditions are specifically excluded from the DDA. These are:

  • Addiction to, or dependency on, alcohol, nicotine, or any other substance (other than in consequence of the substance being medically prescribed)
  • Seasonal allergic rhinitis (for example, hay fever), except where it aggravates the effect of another condition
  • Tendency to set fires
  • Tendency to steal
  • Tendency to physical or sexual abuse of other persons
  • Exhibitionism
  • Voyeurism.

A person with an excluded condition may nevertheless be protected as a disabled person if he has an accompanying impairment which meets the requirements of the definition. For example, a person who is addicted to a substance such as alcohol may also have depression or a physical impairment, such as liver damage, arising from the alcohol addiction. While this person would not meet the definition simply on the basis of having an addiction, he may still meet the definition as a result of the effects of the depression or the liver damage.


P was an alcoholic. She was diagnosed as suffering with depression. She was signed off sick for over one year and was eventually dismissed. She complained unsuccessfully in the first instance of disability discrimination.

There had been some debate between the parties as to whether the alcoholism was the cause or a symptom of the depression. On appeal, the EAT held that the cause of the depression was not material when deciding whether or not someone was disabled within the meaning of the DDA. The correct approach was to look at whether the impairment fell within the definition of ‘disability’ under the DDA and then look at whether the condition fell within one of the exclusions.

Disability caused by medical treatment

The definition of impairment is sufficiently flexible to include a condition which has come about as a result of medical treatment.

result of the effects of the depression or the liver damage.

K had treatment for prostate cancer and developed minor incontinence as a result. The court held that the impairment was sufficiently closely linked to the condition treated to result from it and was therefore a disability.

People who have been disabled in the past, but aren’t now

Someone who is no longer disabled, but who met the requirements of the definition in the past, will still be covered by the act. For example, a woman who experienced a mental illness that had a substantial and long-term adverse effect on her ability to carry out normal day-to-day activities four years ago, but who has experienced no recurrence of the condition, is still entitled to the protection afforded by DDA, as a person with a past disability.