When researching cases, you need to determine two key things about a case:
1. Case History: has the case been appealed to a higher court, potentially all the way to the Supreme Court of Canada? If it has, the initial and/or subsequent decisions may have been changed, e.g. reversed, by the higher courts;
2. Case Consideration/Treatment: has the case been considered by later cases? If it has, the consideration may be positive or negative (also called judicial consideration/treatment).
As case history and consideration can both affect the precedent value of a case, information on this is made readily available in online case law databases, as part of the case report itself, or by using the database's "cite" feature, e.g. Lexis+ QuickCite and Westlaw's KeyCite. Various symbols are used in the case report to indicate the history and consideration applying to a case; consult the each database's user guide or online help for an explanation of the symbols.
UA Library Research guide:
For more information see “Noting Up” Cases section in An Introduction to Legal Research.