Medical-vocational functional limitations are considered specifically at two points in the Social Security Administration's "sequential evaluation process" for determining disability: at the fourth step of the process to decide whether a claimant can perform work he or she has done in the past and at the fifth and final step to determine whether a claimant can perform any other work, given his or her age, education, and past work experience.
The last two steps of the sequential evaluation process address, in effect, the operative portion of the Social Security disability standard: a claimant's ability to engage in substantial gainful activity. As noted earlier, they are reached only if the process is not cut short at one of the earlier steps which focus on medical evidence alone.
Apart from a residual functional capacity assessment, the determination whether a claimant can perform past relevant work or any other substantial gainful activity involves mostly vocational considerations.
Contested issues concerning a claimant's ability to perform past relevant work often focus on the general nature and requirements of prior jobs, how far back into the claimant's work history does the vocationally relevant past extend, and how long the claimant must have worked at a particular job for it to be considered past work for these purposes.