As a common law jurisdiction, we rely on the legal principle of stare decisis ("let the decision stand") whereby a lower court must follow the legal principle established by a higher-level court in the same jurisdiction.
To ascertain whether a decision is still authoritative, two steps are always necessary. First, researchers must determine whether the judgment has been overturned on appeal or reversed in part -- in other words, they must verify the complete history of the case. Second, researchers must determine how widely and in what way the case has been considered by courts since being handed down. In order to find this information,they must look up the judicial treatment or judicial consideration of the case. Both of these together are known as "noting up."
Researchers not only have to find cases on point but also have to determine if those cases are still "good law"--in other words, whether the case has been overruled or reversed by a higher court since it was decided.
One way of determining the history of a case is via case citators. QuickCite on Lexis Advance Quicklaw and KeyCite on WestlawNext Canada (which combine both "Case History" and "Cases Judicially Considered" information) provide this type of information as well as a list of parallel citations for each court level. There are also equivalent print case citators such as the Canadian Abridgment Table of Cases or Cases Judicially Considered. For further information on using the Canadian Abridgment Table of Cases in print form, see the section on Print Sources.
A case that has been "judicial considered" means it has been in some way mentioned, followed, overruled or discussed by a later case. After conducting some initial research on a topic, it is likely that a researcher will come across at least one relevant case. One of the next steps, then, is to locate cases which have judicially considered that case. Searching for this judicial consideration should yield references to similar cases and to more recent cases which could provide some understanding of how the law has since developed. In addition, these results will reveal just how helpful the original case will ultimately be. In preparing a legal argument or submission it is imperative to "note up" a case in this manner to be sure that a proposed legal argument is not weakened by more recent jurisprudence.
Citators assign a treatment level which indicates to what extent and in what manner a case "considered" the former case and often assign detailed treatment levels such as applied, approved, considered, mentioned, disapproved, discussed, distinguished, explained, followed, referred to, or overruled. Though the treatment codes serve as a useful guide, looking at each case directly is the only way to fully understand the extent to which a case was considered.
Cases citators can produce long lists of cases. You would normally only read the significant cases that considered your case: for example, appellate cases, cases from your jurisdiction, and cases that either distinguished or did not follow your case.
The next three sections outline three different sources for finding cases judicially considered. There is substantial overlap in these sources, but each also includes unique cases, so only checking one source could risk not uncovering relevant cases.