This lesson explains how to make sure your case is still "good law." Focusing on print and on-line citators, specifically Shepard's, LexisNexis Shepard's on-line, and Westlaw KeyCite, it builds on concepts introduced in various CALI lessons including: " Legal Research 101: The Tools of the Trade"; "Legal Research Methodology"; "How to Find Case Law Using Digests"; and "Hold'em, Fold'em, Walk Away or Run: When to Stop the Search." This lesson assumes a basic understanding of case law including the specific parts of a reported court decision. This lesson may be used as an introduction to the subject, and also as a review at the end of a legal research course, or before moving to more advanced legal research projects or courses. The lesson provides an option to move directly from the introductory material to on-line citators, skipping citators in print.