20 C.F.R. § 404.1562
(a) If you have done only arduous unskilled physical labor. If you have no more than a marginal education (see § 404.1564) and work experience of 35 years or more during which you did only arduous unskilled physical labor, and you are not working and are no longer able to do this kind of work because of a severe impairment(s) (see §§ 404.1520(c), 404.1521, and 404.1523), we will consider you unable to do lighter work, and therefore, disabled.
Example to paragraph (a):B is a 58-year-old miner's helper with a fourth grade education who has a lifelong history of unskilled arduous physical labor. B says that he is disabled because of arthritis of the spine, hips, and knees, and other impairments. Medical evidence shows a “severe” combination of impairments that prevents B from performing his past relevant work. Under these circumstances, we will find that B is disabled.
[68 FR 51163, Aug. 26, 2003]