The Legal Citator is a tool which allows you to track the history of your case and the treatment of your case by subsequent courts. It allows you to determine if your case is still good law and it acts as a research tool allowing you to find other cases (and other secondary materials) which cited your case.
The legal Citator is used for a number of reasons. One reason is to find a case or statute's direct history. With cases, one can find prior and subsequent history. With statutes, one can find whether the statute was amended or if there is pending legislation, for example. Another reason to use a citator is to identify negative treatment (such as if the case has been overruled) or to find positive treatment (such as another case that agrees with the analysis of your case). Citators can also be used to find additional primary and secondary sources. Finally, there are practical and ethical considerations. Lawyers must be thorough and prepared, and part of that involves making sure that the cases or statutes cited are still good law and can be used as precedent.
The major online citator is the Legal Citator through LexisNexis. Online citators provide a legal researcher with information on how a particular case, legal issue in a case, statute or regulation has been treated by the courts or the legislator or cited in secondary sources.
The citator in LexisNexis are both:
Validation Tool: The citator determines what happened to your case, statute, or regulation after it was released. (has it been reversed on appeal? been overruled? been treated negatively by a subsequent court?)
Research Tool: The citator provides a reference to secondary sources and citing cases.