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When legal professionals validate authority, the first thing they often notice is the citator indicators.
An indicator provides an immediate visual cue about how a case has been treated by later courts, helping researchers quickly determine where to focus their attention. But not all citators communicate the same amount of information.
A recent LexisNexis® study1 comparing Shepard's Signal™ and Westlaw® KeyCite® found a striking difference in how each system flags the same set of cases. While KeyCite leaves more than three-quarters of cases without any flag, Shepard's provides editorial guidance for nearly every case through a broader range of indicators.
The findings illustrate two different approaches to helping legal researchers evaluate precedent.
In a June 2026 study by LexisNexis, researchers entered a single search of “admissibility of evidence” in Westlaw®, limited to the date range of 2004–2024. Researchers then compared the KeyCite flags to the Shepard's Signal™ indicator assigned to the first 1,000 cases that appeared in both Westlaw and Lexis®.
By examining the same 1,000 cases across both platforms, the study focused solely on how each citator communicates the treatment of judicial opinions.
At first glance, both Shepard's ® and KeyCite ® serve the same purpose: helping researchers determine whether a case deserves closer examination.
The difference lies in how much information each system communicates before a researcher even opens the citator report.
KeyCite ® primarily uses two warning flags:
If neither condition applies, the case receives no flag.
Shepard's ® takes a broader editorial approach, assigning Shepard's Signal™ indicators that identify not only negative treatment but also questioned validity, positive treatment, and significant analytical discussion. Shepard's Signal indicators include:
This broader service provides researchers with additional context before they begin reviewing citing references.
When the results of the 1,000-case comparison are visualized, the contrast is immediately apparent.
More than three out of every four cases in the study appeared without any KeyCite flag.
Rather than leaving most cases without editorial guidance, Shepard's assigned a Shepard's Signal ™ indicator to 98.7% of the cases examined.
The difference is significant. While both services identify cases that are no longer good law at nearly identical rates (2.4% versus 2.6%), Shepard's ® provides substantially more information about the remaining cases.
Legal research is about much more than identifying cases that have been reversed or overruled.
Researchers also want to understand questions such as:
A service that primarily identifies negative treatment answers one important question.
A service that also indicates positive treatment, questioned validity, and analytical discussion helps researchers answer several more.
For example, nearly half of the cases in this study received a blue Shepard's Signal ™ indicator, indicating that subsequent courts had meaningfully analyzed, interpreted, explained, or construed the decision. Another quarter of the cases received a green indicator, reflecting positive judicial treatment such as being followed or affirmed.
Neither of these categories would receive a KeyCite flag.
Shepard's Signal ™ indicators are often the first piece of information researchers see in search results.
Because Shepard's ®categorizes a broader range of judicial treatment, researchers receive additional editorial context before opening a case or reviewing its citing references.
Instead of seeing no indicator at all, researchers can immediately recognize whether a case has:
That additional context can help researchers prioritize which authorities deserve closer review and better understand how a case fits within the broader body of precedent.
The study also highlights an important distinction in the purpose of a citator.
Determining whether a case is still good law remains essential, and both Shepard's and KeyCite identify cases that have been reversed or overruled at nearly identical rates.
But validating authority involves more than identifying invalid precedent. Researchers must also evaluate the strength, influence, and subsequent treatment of cases that remain good law.
By indicating positive treatment, questioned validity, and analytical discussion in addition to negative treatment, Shepard's provides researchers with a more comprehensive editorial picture of how courts have engaged with a decision over time.
The June 2026 LexisNexis study comparing 1,000 cases demonstrates two distinct approaches to citator signaling.
Comparison data based on information available as of June 2026. Study conducted by LexisNexis comparing Shepard's® Signal™ and Westlaw® KeyCite® across the first 1,000 common cases identified using the methodology described herein.
KeyCite communicates negative treatment through red and yellow flags but leaves 77.3% of cases without any signal.
Shepard's, by contrast, provides editorial indicators for 98.7% of the same cases, using five distinct indicators to communicate not only negative treatment but also questioned validity, positive treatment, and meaningful judicial analysis.
For legal researchers, that difference means a search results page can provide much more than a warning about bad law. It can offer immediate editorial insight into how a case has been interpreted, applied, questioned, and relied upon throughout its legal life—helping researchers make faster, more informed decisions about where to focus their analysis.
Study conducted in June 2026. Comparative claims expire June 2027. 1 LexisNexis and the Knowledge Burst logo are registered trademarks of RELX Inc., registered in the U.S. or other countries. Westlaw and KeyCite are registered trademarks of West Publishing Corporation. Other products or services may be trademarks or registered trademarks of their respective companies. Copyright © 2026 LexisNexis.