There is no agreement on the definition and measurement of disability. The meaning assigned to the term depends on the uses to be made of the concepts. SSA’s focus in both the SSDI and the SSI programs is on work-related disability, as defined in the Social Security Act. It defines disability (for adults) as the inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or that has lasted, or is expected to last, for a continuous period of not less than 12 months. An individual’s physical and mental impairment(s) must be of such severity that he or she not only is unable to do the previous work but cannot, given the person’s age, education, and work experience, engage in any other kind of substantial gainful work that exists in the national economy, regardless of whether such work exists in the local area, or whether a specific job vacancy exists, or whether the person would be hired if he or she applied for work.
The Social Security definition of disability was developed in the mid-1950s at a time when a greater proportion of jobs was in manufacturing and more required physical labor than today. It was therefore expected that people with severe impairments would not be able to engage in substantial gainful activity. Over the years, many changes have occurred: the nature of work has shifted from manufacturing toward service industries; medical and technological advances have made it possible for more severely disabled persons to be employed; and in recent years, public attitude also has changed as reflected in the enactment of the Americans with Disabilities Act of 1990 (ADA).
In recent years the concept of disability has shifted from a focus on diseases, conditions, and impairments per se to more on functional limitations caused by these factors. Critics suggest that the SSA’s definition of disability and its process for determining program eligibility have not kept pace with the changes. The committee recognizes the administrative difficulties involved in paying more attention in the disability determination process to the physical and social factors in the work environment. Moreover, it might require major shifts in the orientation of the Social Security disability programs to ways to influence the environment in which the applicant might work and to “return-to-work” activities, and might ultimately involve changes in SSA’s implementing regulations.