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Statutory Research Basics


What is a Citator?

Black's Law Dictionary Defines "Citator" as: “A catalogued list of cases, statutes, and other legal sources showing the subsequent history and current precedential value of those sources. Citators allow researchers to verify the authority of a precedent and to find additional sources relating to a given subject.”  Black’s Law Dictionary (11th ed. 2019).

Citators are one of your most useful tools to help with your research. With how swiftly the law changes citators allow you to verify that your research is as current as possible and you are using the correct law. Lexis, Westlaw, and Bloomberg all have their own citators and different ways to use them to make your research easier. 

For additional information please see our guide on Citators.


Shepard's is Lexis’s citator. Similiar to KeyCite, Shepard's uses signals to indicate negative treatment or negative history. 


 Positive Treatment: This tells you that there have been cases that had a positive impact on yours in some way

                             Warning (Statutory): This tells you that citing references contain some negative treatment regarding your case. This may be that it has been found unconstitutional or void 

 Warning: This tells you that citing references contain negative history or that the case may have been overruled in at least one point of law.

 Questioning: This tells you that citing references contain treatment that questions the validity of at least on point of law in your case. 

Caution: This means there is history of treatment that has a negative impact on your case. 

 Neutral: This means there are citing references for your case but they are neither negative nor positive. 

 Information Available: This means there are citing sources available for your case but they do not have history or treatment analysis. These could be secondary sources. 

A synopsis of Shepard’s information is located on the right side of the case. The synopsis shows: prior or subsequent history; number of citing decisions (with signals indicating whether treatment is positive or negative) and number of other citing sources.

Researchers can click individual items in the synopsis or they can choose to  “Shepardize this document” for the complete report (including table of authorities).

KeyCite is Westlaw’s citator. It will help you determine if a source is still good law.

A red flag tells you a case has been overturned on at least one point of law. (e.g., overruled or reversed)

yellow flag tells you that your case has negative history but has not been overturned. (e.g., another court has distinguished a holding in the case).

A blue-striped flag tells you the case has been appealed either to the U.S. Court of Appeals or the U.S. Supreme Court

Overruling Risk is an additional feature which will tell you if a case you are citing relies on overturned authority. This is helpful if your case was not directly overturned but an earlier case was, making yours no longer good law. You can learn more here.

 Clicking on the flags or selecting the "negative treatment" tab above the case will take you to a page which explains why the case has been flagged and other related cases.

KeyCite tabs are automatically listed at the top of each case.  The tabs include: filings, negative treatment, history; citing references (with depth of treatment bars) and table of authorities.

BCite is Bloomberg Law's citator tool. Similar to Shepard's and Keycite, BCite will help you find out if your research is still good law.

You can use this citator  to track the history and subsequent treatment of a case. You can also use it to find secondary sources and other related cases. BCite is available on the right sidebar of court opinions on Bloomberg. Click the "Direct History" and "Case Analysis" tabs at the top of BCite to see treatment of your case by other courts. You can use filters to narrow down the BCite results.