Paul Hellyer, Evaluating Shepard’s, KeyCite, and Bcite for Case Validation Accuracy, 110 Law Libr. J. 449 (2018), https://www.aallnet.org/wp-content/uploads/2018/12/LLJ_110n4_02_hellyer.pdf

“This study evaluates and compares how accurately three legal citators (Shepard’s, KeyCite, and BCite) identify negative treatment of case law, based on a review of 357 citing relationships that at least one citator labeled as negative. In this sample, Shepard’s and KeyCite missed or mislabeled about one-third of negative citing relationships, while BCite missed or mislabeled over two-thirds. The citators’ relative performance is less clear when examining the most serious citator errors, examples of which can be found in all three citators.” (via Mary Whisner)