Under the Social Security Act, disability means "...inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment [or combination of impairments] which can be expected to result in death or has lasted or can be expected to last for a continuous period of not less than 12 [consecutive months]...[taking into account the individual’s age, education and work history]." (42 U.S.C. §§ 423(d), 1382c(a)(3)(B); 20 C.F.R. §§ 404/1505, 416.905.)
In layman’s terms, this means that an individual who suffers a serious illness or injury and expects to be unable to work for at least one year or more may file a claim for Social Security disability benefits.