When Social Security Security evaluates a claim for disability, it uses a 5-step sequential evaluation. For steps 4 & 5 of the sequential evaluation, Social Security assesses your functional limitations and incorporates those limitations into a Residual Functional Capacity (RFC). That RFC is then compared to the requirments of competitive work to determine whether or not a person claiming disability is disabled under Social Security's rules.
When evaluating a claim for disability, the RFC assessed by the state Disability Determination Services (DDS) should always be the starting place. What limitations did the state agency find? What work would be precluded by the RFC? These are the first questions to ask when evaluating a claim.
From this starting place, you can then evaluate the medical evidence to see what evidence may be missing and what could be supplemented. As always, opinions from a treating medical source regarding a patient's functional limitations is highly desirable.
An administrative law judge also look first at the DDS RFC. I had this discussion with an ALJ after a hearing recently, and that judge always uses the DDS RFC as a starting point (and sometimes, a finishing point). Even though an ALJ hearing is a de novo review of the claim, the DDS RFC is always considered.
If an ALJ will always begin with the DDS RFC, then that raises the issue of early involvement by a lawyer in a disability claim. If you can move the RFC closer towards disability aat the state agency level, then you may have an easier time establishing disability at your ALJ hearing. You may also win your case at Reconsideration, which is even better. Either way, the early involvement of a disability lawyer can help to frame the issues and develop the evidence well before the judge takes a first look at the case.