The main function of the fifth of the five-step sequential disability determination process is for the SSA to prove that the claimant is able to perform other jobs that exist in significant numbers; one method of demonstrating that a significant number of jobs exist in the national economy is through the use of the Grids.
The Grids cannot be applied to claimants who have non-exertion characteristics because the Grids were constructed to apply only to claimants' exertional abilities. Thus, if the Grids are not applicable, because either the Grids cannot be applied or because the claimant's RFC or relevant vocational factors are different from those reflected in a particular grid rule, the SSA must use other means of proving that jobs exist that the claimant can perform.
The most common way to prove that jobs exist is through the use of the testimony of the VE. The ALJ directs questions to the VE that incorporate hypothetical situations. The ALJ's hypothetical questions presume that the facts presented in the claimant's case are true. The hypothetical questions start with the least restrictive RFC for work, and subsequently, the ALJ adds new limitations to each additional hypothetical question.
In this fifth step, the VE plays his or her most significant role in the disability determination process. The VE testifies regarding whether, using the claimant's RFC and the ALJ's hypothetical limitations, in comparison with employment data taken from the DOT, the claimant can perform other work that exists in significant numbers within the national economy.
Essentially, the VE's testimony--which supports a finding that in view of the claimant's age, education, and work experience other work exists or does not exist in the national economy--is based on data from the DOT. The claimant is assured that the SSA relies on reliable job information available from various publications, including the DOT and other documents, as provided by the regulations. Thus, as determined by the ALJ after relying on the testimony of the VE, the claimant is entitled to DIB only if a significant number of jobs that he or she is able to perform is not available in the national economy.
Section 405(g) of the SSA allows unsuccessful claimants to seek judicial review of the ALJ's decision. However, the scope of judicial review in such cases is limited because the SSA's denial of benefits is not to be disturbed if it is supported by substantial evidence and contains no legal error.
In regard to Social Security disability proceedings, substantial evidence is "more than a mere scintilla, but may be less than a preponderance." Indeed, the ALJ's resolution of evidentiary conflicts requires such deference. Considering the high level of deference given to the SSA with regard to evidentiary matters, and the relatively broad credibility granted to VE testimony, questions of reliability and fairness are bound to arise in Social Security disability proceedings. The lack of concrete standards regulating the methodology used by VEs is the key factor undermining the integrity of the five-step sequential disability determination process. For this reason, the next section addresses the progression of evidentiary standards as they apply to expert witnesses, as well as the SSA's attempt to curb the broad credibility granted to VEs.