One theme from 1L legal research classes is that legal research tools all have their shortcomings, and careful researchers should make informed choices about how they use them. A recent white paper demonstrates that “how was this case cited” reports are not all created equal. (Spoiler: in some cases, the expensive ones do a much better job.) The authors do, however, note a workaround:
While we recommend NOT relying entirely on any of the citator services provided by Google Scholar, Fastcase, or Casemaker, legal researchers can still use these databases to learn if their cases are still good law by taking the extra step to run a search using the party names as keywords. . . You’ll need to read the resulting cases (but only those decided after your case was decided) and then discern for yourself how the subsequent cases treated your case.
Carole A. Levitt and Mark Rosch. Are all Citator Services Created Equal? A Comparison of Google Scholar, Fastcase, Casemaker, LexisNexis, WestlawNext, and Bloomberg. (PDF, ePub, and Kindle-friendly versions available online at netforlawyers.com; PDF also available online from Stanford Law Library.)