Nexis Uni offers Shepard's citations for cases, regulations, and statutes.
A formal definition: "Shepard’s Citations provide a judicial history of cases and statutes, make note of new cases, and indicate whether the law in a particular case has been followed, modified, or overruled in subsequent cases... various abbreviations indicate whether a case has been overruled, superseded, or cited in the dissenting opinion of a later case."
"Shepard’s® Citations." Gale Encyclopedia of American Law. Ed. Donna Batten. 3rd ed. Vol. 9. Detroit: Gale, 2010. 176. Gale Virtual Reference Library. Web. 19 Aug. 2015.
This course guide offers information on how to find taxation cases, regulations, and statutes in Nexis Uni. It also includes related sources from the books, journal articles, and websites. Please contact me if you have questions.