BOX 3-1: Tower of Disability Babel

The endeavor to define disability in the ADA is not unprecedented. As noted in chapter 2, the ADA's specifications stem from a series of disability laws, regulations, and court decisions. Definitions of disability have evolved over the course of the 20th century, reflecting program, policy, and research needs. This box describes various models and definitions of disability as well as inconsistencies that flag the potential for conflict among disability programs and policies.

A recent study by the Institute of Medicine (IOM) described two major models for defining disability: the functional limitation model, developed by Nagi, and the World Health Organization (WHO) model. Both acknowledge three critical factors in disability: underlying impairment, functional result, and environmental influences. But they differ in their terminology and application.

The functional limitation model includes four stages on the path toward disability: pathology, impairment, functional limitation, and disability (figure 3-1, not available). The concept of pathology refers to an abnormal change in a normal bodily process or structure that results from such factors as infection, trauma, or developmental process. Impairment reflects functional restrictions at the organ level, stemming from either pathologies or other mental, emotional, physiological, or anatomical losses or abnormalities. For example, symptoms such as hallucinations in schizophrenia represent an impairment in this framework. Restrictions on an individual's actions or activities--such as lifting a heavy weight or carrying on a coherent conversation--form functional limitations. Disability refers to impaired performance of a socially defined role, reflecting an impairment or functional limitation and environmental supports and demands. This model notes that a variety of factors, such as treatment, financial resources, or personal expectations, can impinge on any stage. The model also asserts that disability is not the inevitable result of a pathological condition, impairment, or even functional limitation. The WHO model for defining disability--WHO's 1980 International Classification of Impairments, Disabilities, and Handicaps (ICIDH)--is a taxonomy or classification system. Currently under revision, it is the most widely used system for classification in the world. Like the functional limitation model, the WHO model builds on four concepts: disease, impairment, disability, and handicap. The concept of disease stems directly from the medical model, referring to pathology in an individual. Impairment is any loss or abnormality of physiological, psychological, or anatomical structure or function. Disability results from impairment, referring to the inability or restricted ability to perform activities considered within the range normal for humans. Finally, a person is said to have a handicap when an impairment or disability limits or prevents role performance for that individual in society. Note that IOM's concept of disability is equivalent to handicap in WHO's model. Some, including the IOM, have criticized the ICIDH because of internal inconsistencies and the use of the term handicap, which generally is rejected as stigmatizing in the United States.

Public health entities are not the only ones to define disability. In fact, the first definitions of disability came from rehabilitation, compensation, and insurance programs. Three programs, with differing definitions of disability, may be particularly relevant to the ADA's implementation:

Social Security Disability Programs: The U.S. Social Security Administration (SSA) operates two disability income maintenance programs. The Social Security Disability Insurance (SSDI) program is an insurance program for those who have become disabled. The Supplemental Security Income (SSI) program is a social welfare program for people who are blind, aged, or disabled. In both SSDI and SSI, people with psychiatric disabilities form the largest portion of beneficiaries. In 1991, 24 percent of SSDI beneficiaries received financial support on the basis of mental disorders. In that same year, 27.4 percent of SSI beneficiaries with disabilities received financial support on the basis of mental disorders. Eligibility for these income-support programs hinges on the strictest of all definitions of vocational disability. As detailed in the Federal Social Security Act, disability is "the inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment(s) which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months. "Guided by the statutory language, SSA developed an administrative procedure to determine disability status, based on medical and nonmedical evidence.

Vocational Rehabilitation: The Rehabilitation Services Administration (RSA) administers vocational rehabilitation (VR) services, including employment potential assessment, vocational training, job placement, and followup support, under a Federal-State program. The Rehabilitation Act originally authorized the VR program in 1920 to help injured workers return to their jobs. Since 1975, amendments to the Rehabilitation Act gives priority of services to people with severe disabilities--"persons who need multiple services over an extended period of time"--but who had demonstrable employment potential. The 1992 reauthorization reconciles the language and ideals of the VR program with those of the ADA. The law also specifies that people with the most severe disabilities should be served, asserting that any individual is employable given the proper support services and technology. Today, people with psychiatric disabilities are the second-largest group of applicants for VR services--17 percent of the client population served. However, experts and advocates claim that these individuals are underserved by this program and that vocational services remain a major need for this population. Data from the RSA indicate that people with psychiatric disabilities have the lowest rate of successful rehabilitation under this program.

Workers' Compensation: Lost wages or earning capacity due to an employment-related injury or illness provides evidence of disability in workers' compensation programs. While varying somewhat among jurisdictions, eligibility determinations generally rest on medical documentation and resulting inability to work. Rather than relying on an either/or proposition--disabled or not--information on the relative degree of disability (Is the disability temporary or permanent ? partial or complete?) is sought. Benefits in workers' compensation may cover medical care, wage replacement and compensation, and rehabilitation services. In the last 10 years, as wages and medical costs have increased, workers' compensation costs have risen significantly. The changing nature of work and evolving definitions of work-related disorders also have spawned new categories of disabilities. Stress-related disorders represent one example. In California, they account for a 700 percent increase in claims between 1979 and 1988. Much debate surrounds the issue of fraudulent claims, the subjectivity of claims, as well as the difficulty such disorders present in separating job-related causes from aggravating personal factors. As this review of the programs and academic models reveals, all consider impairment and its functional results as key concepts of disability, but their definitions differ. Impairments can mean any impairment, or only those that result from injury on the job. Functional results can mean the inability to work over a long period of time, or refer to a temporary hiatus. Such distinctions are unavoidable with different program goals, and the ADA adds yet another set of definitions.

Confusion, conflict, and inefficiency evolve from this "tower of disability Babel," however. While a common nomenclature may not be possible, given the different policy and program goals, guidance on the jurisdictional overlaps would greatly assist employers, care providers, and those who enforce disability policy.

For example, some experts claim that compliance with the ADA in providing an accommodation for an injured worker can save employers money in workers' compensation, by putting the employee back to work. On the other hand, injured workers with no desire to return to work may use the ADA to increase workers' compensation settlements. Or, employers trying to limit the spiraling costs of workers' compensation, may medically screen out workers who may pose an increased risk of benefit utilization; this practice is forbidden by the ADA. The interplay of these different policies and programs warrants attention, both monitoring and guidance.

So does determining disability. Many different experts-- medical, psychological and rehabilitative--have considerable skill in this area. However, experience has shown that clinicians usually equate disability with a medical diagnosis, a determination that is not necessarily applicable under ADA. The development and dissemination of disability assessment methodologies that apply to different policies and programs may assist clinicians. It would also be helpful if academic models and classification systems better reflected program and policy language to provide a cross-walk between research and public policies, and if disability research reflected the policy definitions in use.

It is also notable that psychiatric disability has not always had an easy fit with disability models and programs. In each program discussed in this section--Workers' Compensation, SSDI and SSI, and VR--psychiatric disabilities have led, at one time or another, to controversy, fraudulent claims and abuse ,and/or people being underserved. The debate surrounding workers' compensation and stress-related conditions was mentioned above. SSI and especially SSDI still pose work disincentives for people with psychiatric disabilities, although there have been some recent improvements. Also, experiences with SSI and SSDI in the early 1980s, and continuing in the VR program, show significant gaps in the service provided people with psychiatric disabilities. Not only are people with psychiatric disabilities among the largest constituencies in these programs, they are also among the most vulnerable because of stigma, the nature of their impairments, and service and support needs. These conditions also raise complex questions because of their behavioral manifestations and subjectivity of claims. This suggests that effective implementation of the ADA will hinge on accurate information on psychiatric disabilities and consideration of the special issues raised by this population. Advance attention to problems that occurred in other programs could prevent them in the ADA.


H. Andrews, J. Barker, J. Pittman et al., "National Trends in Vocational Rehabilitation: A Comparison of Individuals With Physical Disabilities and Individuals With Psychiatric Disabilities," Journal of Rehabilitation January-March:7-16, 1992; California Workers' Compensation Institute, Mental Stress Claims in California Workers' Compensation--Incidence (San Francisco, CA: California Workers' Compensation Institute, 1990); Institute of Medicine, Disability in America: Toward A National Agenda for Prevention, A.M. Pope and A.R. Tarlov (eds.) (Washington, DC: National Academy Press, 1991); C. Kennedy, and E.M. Gruenberg, "A Lexicology for the Consequences of Mental Disorders," Psychiatric Disability: Clinical, Legal and Administrative Dimensions, A.T. Myerson and T. Fine (eds.) (Washington, DC: American Psychiatric Press, 1987); C. Kennedy and R.W. Manderscheid, "SSDI and SSI Disability Beneficiaries With Mental Disorders," Mental Health, United States, 1992, R.W. Manderscheid and M.A. Sonnenschein (eds.), DHHS Pub. No. (SMA) 92-1942 (Washington, DC: Superintendent of Documents, Government Printing Office, 1992); J.G. Kilgour, "Workers' Compensation Problems and Solutions: The California Experience," Labor Law Journal February:84-96, 1992; J.C. McElveen, Jr., "Recent Trends in Workers' Compensation," Employee Relations Law Journal 18:255-271, 1992; M.D. Tashjian, B.J. Hayward, S. Stoddard et al., Best Practice Study of Vocational Rehabilitation Services to Severely Mentally Ill Persons, Volume I: Study Findings (Washington, DC: Policy Study Associates, 1989);World Health Organization, International Classification of Impairments, Disabilities, and Handicaps (Geneva, Switzerland: World Health Organization, 1980).

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