… as we approached the 1950s, it looked like disability insurance was coming—and we had to study how it would be administered. I found that there was little or no appreciation and no detailed work being done on how Social Security would go about administering various conceivable provisions (Hess, 1993:6, 7).
Early on, officials at the Social Security Board decided that the definition of disability for any disability benefit program had to be a strict one to be politically acceptable and financially feasible. They also recognized that the concept of disability was highly elastic and that determining disability was likely to be quite imprecise. They thought that too strict a definition might result in pressure to “swing in the opposite direction” (Berkowitz, 1987:44). The definition they chose, which became the model for the definition that was eventually adopted in the legislation establishing the disability freeze and disability insurance benefit programs many years later, was borrowed from the War Risk Insurance Act (administered by the Veterans Administration), which defined disability as:
Any impairment of mind or body which continuously renders it impossible for the disabled person to follow any substantial gainful occupations, and which is founded on conditions which render it reasonably certain that the total disability will continue throughout the life of the disabled person (cited in Berkowitz, 1987:44).
The definition of disability eventually adopted in the Social Security Amendments of 1954 was:
Inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or to be of long-continued and indefinite duration (cited in SSA, 1996:2).
The Social Security definition of disability has evolved over the last 50 years, especially in the 1960s. In 1965, the definition was changed, easing the strictness of the duration requirement. Impairments were no longer required to “be of long-continued and indefinite duration.” Rather, the impairment only had to last or be expected to last for 12 months. In 1967, the law was again amended in response to a series of judicial decisions that placed an increasing burden on the SSA to establish the existence of jobs that denied applicants might reasonably obtain. The change in the definition was intended to emphasize its medical focus by providing that an individual would be found disabled “only if his physical or mental impairment or impairments are of such severity that he is not only unable to do his previous work but cannot, considering his age, education, and work