Social Security Rulings are policy interpretations issued by the SSA. Social Security Rulings are binding on all components of the SSA, and are to be relied upon as precedents when adjudicating other cases. See 20 CFR 402.35(b)(1).
Social Security disability lawyers refer to the Rulings regularly. The Rulings contain very useful explanations of SSA's policy, and offer more detail than the regulations. If there is a Ruling on a topic at issue in your case, that Ruling is mandatory reading for your disability lawyer.
Sometimes, however, it can take a little while to find the particular ruling you need. This is partly due to the Rulings' odd numbering system.
Recently, the SSA published a new index of the rulings, grouping them by subject matter. It is a very helpful index, and I have added it to the "Resources of Note" section on the sidebar of this blog.
Hat tip to JOA on the Connect discussion board for the catch.