Many tax database allow users to shepardize a tax case, an IRC section, IRS regulations, IRS documents, and so on to find other legal materials and publications that cite the pertinent material.
"The CCH Citator tracks the history of cases and ruling through the legal process and indicates whether a case or ruling is still current." (CCH) Click on "Citator" from the blue bar.
"Key Cite Tax Citator now functions at the code subsection and paragraph level, so you can quickly and easily retrieve a list of cases and statues, proposed legislation, administrative decisions and analytical sources on Westlaw citing a code subsection or paragraph." (Westlaw) Click on KeyCite on the top banner.
