As noted earlier, during the last forty years, there has been a rapid evolution of thought about the nature and meaning of “disability”. Today, there exist multiple competing perspectives and the notion of “disability” is the subject of wide-ranging and complex discussion and controversy.
It is not the purpose of this Paper to fully canvass all of these perspectives and debates; given the complexity and multiplicity of the issues, that would require a very lengthy document. This portion of the Paper will provide highlights of some aspects of these concepts and debates, insofar as they are relevant to the development and understanding of legal definitions of disability, and the approach to be taken in this Project.
Scholars have categorized concepts of disability in various ways. Generally, the axis of differentiation has revolved around the role of ‘impairment’ in the experience of disability. Many scholars therefore categorize conceptual approaches to disability into two broad groupings: one focussed on impairment and the other on the social construction of disability. This is the fundamental distinction. However, based on a review of concepts of disability as they are revealed in statutory definitions of disability and the accompanying caselaw, it may be helpful to further breakdown these two categories. The LCO has therefore categorized legal definitions of disability in Ontario into four conceptual approaches:
Recently, there is some movement towards the development of a mixed model, although this has not yet been reflected in legal structures.
The four categories here identified are similar to the categorization adopted by the federal government in its analysis of definitions of disability, and therefore allows comparisons across jurisdictions. It should be noted that, not infrequently, laws combine multiple approaches into a single definition.
Each of these conceptual approaches to disability will be described below, together with examples of how these approaches have been implemented in law and public policy.
B. Bio-Medical Approach
1. The Approach: Impairment and Disability
To a substantial degree, debates about the nature of disability turn on the role of physical, mental, sensory, cognitive or intellectual impairments in disabling individuals, versus the role of societal attitudes and structures.
Popular understandings of the nature of disability, as well as many policy and legal frameworks centre on the notion of disability as resulting from physical, sensory, psychiatric, cognitive or intellectual impairment. That is, disability is intrinsic to the individual who experiences it. In this model, impairments are dysfunctions that have the effect of excluding persons with disabilities from important social roles and obligations, leaving them dependent on family members and society. As such, disability is an individual tragedy, and a burden on family and society.
This bio-medical conception of disability was the dominant policy model for understanding disability until the last few decades of the 20th century, and remains ascendant in the popular understanding of disability
Under this approach, the most appropriate policy response to disability is medical and rehabilitative. The aim is to overcome, or at least minimize, the negative consequences of individual disability. Individuals with disabilities may therefore become the focus of intensive and sometimes coercive expert attention focused on accurately identifying and “fixing” the impairment causing the disability.
The focus on “fixing” persons with disabilities may lead to assumptions that persons with disabilities are defective and abnormal, and therefore in some way inferior to, and less worthy of consideration than persons who do not have a disability.
2. Statutory Definitions Using the Bio-Medical Approach
Under the bio-medical approach, expertise regarding the nature, causes and responses to disability resides with medical and rehabilitative professionals. This approach defers to these professionals in identifying who has a disability and prescribing appropriate rehabilitative or other strategies for addressing the disability.
While statutes now rarely use lists of bio-medical conditions in defining disability, it is still common for statutes to defer the determination of disability entirely to medical professionals without other definition, an approach that implicitly incorporates a bio-medical model of disability, by leaving determinations about eligibility for important programs, benefits and services to the discretion of individual medical practitioners.
For example, the Homes for the Aged and Rest Homes Act provides special evidentiary procedures for persons who are unable to attend a hearing because of age, infirmity or physical disability. It provides no definition of “physical disability”, but requires certification by a medical practitioner.
Other statutes require medical practitioners to certify that the person in question has the asserted limitation or impairment. For the purposes of defining eligibility for specialized day nursery programs, the Day Nurseries Act includes a functional definition of a “handicapped child”, but requires medical certification:
“handicapped child” means a child who has a physical or mental impairment that is likely to continue for a prolonged period of time and who as a result thereof is limited in activities pertaining to normal living as verified by objective psychological or medical findings and includes a child with a developmental disability.
Certification may be provided by a member of the College of Physicians and Surgeons of Ontario, a member of the College of Psychologists of Ontario, a member of the College of Optometrists of Ontario, or a member of the College of Nurses of Ontario who holds an extended certificate of registration.
Specialized transit programs very commonly require medical certification of a mobility-related impairment. Kingston Access Bus, for example, provides specialized transit services for “individuals with physical disabilities regardless of age who, due to a mobility impairment, are unable to use conventional transit facilities”. Applicants for this service must have their physicians fill out and certify the application form, detailing the type and severity of the mobility-related impairment. 
Other statutes do not explicitly require medical verification of disability, but in practice determinations regarding eligibility rely heavily on information provided by medical practitioners. For example, Regulation 181/98 under the Education Act sets out the process for the identification and placement of exceptional pupils. Regulation 181 does not require parents to provide professional certification of their child’s exceptionality, specifying only that the Identification, Placement and Review Committee must consider any educational, health or psychological assessment placed before them, as well as information submitted by parents. In practice, the accommodation process under the Education Act may be heavily weighted towards professionals.
There is considerable literature on the power that this model gives medical practitioners over the lives of persons with disabilities. Medical diagnoses become key to accessing rights and disability-related supports and benefits. Persons with disabilities are expected to defer to medical professionals, and may be labeled as non-cooperative and unreasonable if they fail to do so. As medical professionals become the gatekeepers of scarce resources, persons with disabilities who are not “model patients” are at risk of being dismissed or disbelieved. This reliance on medical and health professionals has been critiqued as placing persons with disabilities in a position of dependence, and giving professionals excessive power to label, evaluate and define persons with disabilities.
3. Learning from Examples
i. Environmental Sensitivities
Some of the limitations of a legal approach to disability based on a bio-medical approach are revealed by examining the treatment in law of persons with environmental sensitivities.
Medical consensus regarding diagnostic criteria and causation for the condition known as environmental sensitivity is still developing. The clinical picture is complex: there is no single, simple condition with a universal cause. The lack of a universally acknowledged bio-medical description and causation for environmental sensitivities has led to difficulties for persons living with this condition in having their experiences recognized as a form of disability and in obtaining appropriate accommodations. Environmental sensitivities may be dismissed as a fabrication or as being “all in their heads”.
Legally, the lack of an agreed-upon bio-medical foundation for environmental sensitivities is not necessarily an overwhelming barrier under human rights statutes, which are less preoccupied with the cause of limitations than with demonstrated accommodation needs. However, as a practical matter, it may create significant difficulties in legal regimes that require scientifically verifiable evidence regarding diagnosis and causation. Where access to rights or benefits depends on the ability to provide expert medical verification of impairment (for example, in accessing disability benefits), the lack of widespread medical recognition and knowledge about environmental sensitivities