SSA defines disability as 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.
A medically determinable physical or mental impairment is an impairment that results from anatomical, physiological or psychological abnormalities which can be shown by medically acceptable clinical and laboratory diagnostic techniques. A physical or mental impairment must be established by medical evidence consisting of signs, symptoms, and laboratory findings – not only the individual’s statement of symptoms; and
The individual must be unable to engage in "Substantial Gainful Activity" due to the impairment.
Substantial gainful activity is any work performed for pay or profit, involving the performance of significant physical or mental duties. The person must be unable to perform his former job, and is unable to work in any other job in the national economy. For current substantial gainful activity amounts, see: http://www.socialsecurity.gov/OACT/COLA/SGA.html.
42 U.S.C.A § 1396A(v)
42 U.S.C.A § 1382C(a)
Reissued September 20, 2006, replacing July 26, 2005; reviewed March 16, 2012