Study Confirms Shepard’s® Delivers More Citation Research Analysis Than KeyCite®

Lawyers have always valued the importance of grounding their legal arguments in “good law” that is current, on-point and accurately cited. The risks of failing to ensure the integrity of their legal research has been prominently on display in the last couple of years as more legal professionals have embraced the power of AI tools, sometimes without properly validating their AI-generated case citations. 

The most important tool that any lawyer must rely upon to have confidence their research contains cases with precedential value is to use a legal citations service that can verify the accuracy and currency of those cites. A comprehensive new study conducted this summer by LexisNexis® reveals a significant disparity in the depth of case analysis provided by the two leading legal citation services. 

The research demonstrates that Shepard’s® Citations Service delivers substantially more analytical content than Westlaw® KeyCite®, marking the fifth consecutive year in the head-to-head study that Shepard’s® has provided legal professionals with a considerable advantage in legal research and case preparation. 

The Study 

The study employed a rigorous comparative methodology to evaluate the performance of both citation services. LexisNexis® legal researchers conducted a targeted search for cases involving insurance and construction law, covering a 20-year period from 2003 to 2023. This substantial timeframe ensured a robust dataset that reflects the evolution of legal precedent across multiple jurisdictions and changing legal landscapes. 

From this search, researchers analyzed the first 1,000 cases available on both LexisNexis® and Westlaw® platforms, creating a direct comparison between the two flagship citation services. The identical case sets eliminated variables that could skew results and provided a clear picture of how each citation service treats the same legal authorities. 

The Findings: Shepard’s® Delivers Triple the Analysis 

The study uncovered some important differences in the performance of Shepard’s® and KeyCite®. Overall, it revealed that Shepard’s® goes beyond verifying good law and empowers lawyers to build a stronger case by citing references that support their positions and offering substantive explanations and interpretations. Here were four highlights of the findings: 

Volume of Analysis 

The study’s most striking finding centers on the volume of substantive analysis provided by each service. While Westlaw® KeyCite® provided some form of analytical treatment for only 17.9% of the cases examined, Shepard’s® delivered analysis for an impressive 96.2% of the same cases. This represents more analytical content, a difference that could provide crucial for legal practitioners building comprehensive arguments. 

Types of Treatment 

The analytical advantage of Shepard’s® over its nearest competitor becomes even more pronounced when examining the specific types of treatment provided. Shepard’s® offered substantive explanations, interpretations and constructions of legal precedent in cases where KeyCite® provided no analytical flags whatsoever. This additional layer of insight can help attorneys understand not just whether a case remains good law, but how courts have interpreted and applied its holdings in subsequent decisions. 

Depth of Categorization 

The study also revealed notable differences in how each system categorizes case treatment. KeyCite® returned no flag designations for 82.1% of cases, suggesting either positive standing or insufficient negative treatment to warrant notification. In contrast, Shepard’s® provided more granular categorization, with only 3.8% of cases receiving no signal indicator. 

Nuances in Classification 

Finally, while both systems showed relatively similar patterns for the most serious classifications — KeyCite® flagged 3.5% of cases as no longer good law due to reversal or overruling, Shepard’s® identified 3.2% in this category —there was once again an important difference in the depth of analysis. Shepard’s® provided additional nuance by separately identifying cases with “validity questioned” (0.5%) and those receiving “possible negative treatment” such as criticism or distinction (16.3%). 

The results indicate that Shepard’s® has extended its lead over KeyCite® in these key areas of citation analysis over the years of the head-to-head research, which started in 2021. The findings suggest that the choice of citation service can have measurable impacts on the quality and comprehensiveness of legal analysis available to support a lawyer’s work. 

Experience Shepard’s® for Yourself 

Shepard’s® is seamlessly integrated with the Lexis+® and Lexis+ AI® platforms, which include access to legal research, data-driven insights, practical guidance and legal news. This allows for effortless workflow — no switching is required between legal research and citation service functions — and maximizes efficiency. 

As AI-powered legal research continues to evolve, the fundamental principles of accuracy, verification and professional responsibility will become even more important in the future. The Shepard’s® Citation Service focuses specifically on ensuring that no links are provided to unverified citations, creating a crucial barrier between AI-generated content and the authoritative legal sources that lawyers depend upon for their work. 

Existing Lexis+ AI® or Lexis+® customers can access Shepard’s® directly within the platform. Legal professionals interested in obtaining access to Shepard’s® can request a free 2-day trial of Lexis+ AI® and look for Shepard’s® Citation Service on the platform.