Under the rules governing the Social Security Administration (SSA), “disability” is defined as “the inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment or combination of impairments that can be expected to result in death or that has lasted or can be expected to last for a continuous period of not less than 12 months.”

SSA has established a five-step sequential evaluation process for determining whether an individual is “disabled” as defined in the rules. The steps are followed in the order set forth below. If it is determined that a claimant for disability benefits does not meet the standard established in any one of the steps, the evaluation will not proceed to the next step and the claimant will be found to be “not disabled” at that time.

At step one, SSA must determine whether the claimant is engaged in substantial gainful activity. Substantial gainful activity (SGA) is defined as work activity that is “both substantial and gainful.” That is, if the claimant is working and his/her earnings average more than $1,000 a month (in 2010), he/she is considered to be engaged in SGA. In that event, a claimant will not be considered to be disabled regardless of how severe his/her physical or mental impairments are and regardless of his/her age, education, or work experience. If the claimant is not engaged in SGA, the evaluation proceeds to step two.

At step two, SSA must determine whether the claimant has a medically determinable impairment that is “severe” or a combination of impairments that are “severe.” An impairment or a combination of impairments is “severe” within the SSA regulations if it significantly limits an individual’s ability to perform basic work activities. If the claimant does not have a severe medically determinable impairment or combination of impairments, he/she is not disabled. If the claimant has a severe impairment or combination of impairments, the evaluation proceeds to step three.

At step three, SSA must determine whether the claimant’s impairment or combination of impairments meets or medically equals the criteria of impairments listed in the regulations at 20 C.F.R. Part 404, Subpart P, Appendix 1. For each of the major body systems, SSA maintains a list of medical conditions that are so severe they automatically result in a finding that the claimant is disabled. If the claimant’s condition is not on the list, SSA must decide whether the condition is of equal severity to a medical condition that is on the list. A claimant is disabled according to the medical listing if he/she has a listed impairment or the impairment is “equal to a listed impairment.” If the claimant has more than one impairment, even if none of them alone satisfies a listed impairment, the impairments, in combination, may be “medically equal” to a listed impairment. If the impairment(s) is not equal to listed impairment, the evaluation proceeds to step four.

SSA has two initiatives at step three which are designed to expedite processing of claims for disability benefits:

• Compassionate Allowances: Certain cases that usually qualify for disability can be allowed as soon as the diagnosis is confirmed. Examples include acute leukemia, Lou Gehrig’s disease (ALS) and pancreatic cancer. (I previously blogged about the Compassionate Allowances Initiative here and here.)
• Quick Disability Determinations: SSA analyzes specific elements of data within the electronic claims file to identify claims where there is a high potential that the claimant is disabled and where evidence of the person’s allegations can be quickly and easily obtained.

In addition to the above, before considering step four of the sequential evaluation, SSA must first determine the claimant’s residual functional capacity (RFC). RFC refers to a claimant’s ability to do physical and mental work activities on a sustained basis despite limitations resulting from his/her impairments. In making the determination, SSA must consider all of the claimant’s impairments, including impairments that are not severe.

At step four, SSA must determine whether the claimant has the RFC to perform the requirements of his/her past relevant work. This means SSA will look at all of the jobs performed by the claimant in the past 15 years and determine what the claimant can still do, despite any limitations caused by the claimant’s impairment(s) and related symptoms, such as pain and fatigue. If, because of the claimant’s impairments (either physical or mental), the claimant can no longer perform the physical and mental demands of past employment based upon the claimant’s residual functional capacity, age, education, and work experience, then the claimant is disabled according to functional factors. In making this determination, SSA will consider both medical and non-medical information. If the claimant is unable to perform any past relevant work or does not have any past relevant work, the evaluation process proceeds to step five, the last step.

At step five, SSA must determine whether the claimant is able to do any other work considering his/her RFC, age, education, and work experience. SSA assesses these factors with the claimant’s capacity to work to determine if he/she can be expected to adjust to other work that exists in the national economy. If the claimant is able to do other work, he/she is not disabled. To make a determination that the claimant is not disabled at this step, SSA must produce evidence demonstrating that other work exists in significant numbers in the national economy that the claimant can do, given his/her RFC, age, education, and work experience. If he/she is not able to do other work, the claimant is disabled.