Purpose of Citation Checking
Citation checking verifies that the legal authorities you rely on are still valid. A case that was "good law" last year might have been overruled, reversed, or called into question since then. If you cite it without checking, you risk building an argument on a foundation that no longer holds.
Two major tools handle this work: Shepard's Citations (on Lexis) and KeyCite (on Westlaw). Both do the same core job but use different symbols and terminology. You need to be comfortable with both.
Validating Legal Authority
The first reason to citation-check is to confirm that your source is still good law. This means verifying that a case hasn't been overruled, a statute hasn't been repealed, and a regulation hasn't been superseded.
- Checks whether the authority has received negative treatment that undermines its value
- Confirms the holding you're relying on hasn't been narrowed or modified
- Protects you from the professional embarrassment (and ethical problems) of citing invalid authority
Identifying Subsequent History
Subsequent history traces what happened to a case after the decision you're citing. Did the losing party appeal? Was the decision affirmed or reversed?
- Shows whether a decision was affirmed, reversed, or modified on appeal
- Reveals remands or rehearings that may have changed the outcome
- Tracks the case through every level of the court system, from trial through final disposition
Finding Related Cases
Citation checking also works as a research tool. When you Shepardize or KeyCite a case, you get a list of every later case that cited it.
- Helps you discover more recent authority on the same legal issue
- Shows how different jurisdictions have applied or distinguished the original case
- Can reveal a line of cases that strengthens (or weakens) your argument
Shepard's Citations
Shepard's Citations is the original citation-checking system, now available electronically through Lexis. It provides a comprehensive report on any case, statute, or regulation, showing how later authorities have treated it.
Origin and Development
Frank Shepard created this system in 1873 to help lawyers track how cases were treated over time. The original format was a set of gummed labels attached to case reporters, listing subsequent citations. Over the decades, these evolved into bound volumes organized by jurisdiction and reporter series. The system moved to electronic format in the late 20th century, and today it lives on the Lexis platform.
Print vs. Online Versions
The print version required you to look up a case by reporter volume and page number, then manually cross-reference entries across multiple supplement volumes. The online version on Lexis offers real-time updates, hyperlinked citations, and the ability to filter results by jurisdiction, date, or treatment type. For practical purposes, you'll almost always use the online version, but understanding the print format helps you grasp how the system is organized.
Components of a Shepard's Report
A Shepard's report contains several key parts:
- Full citation of the Shepardized case or statute
- Subsequent appellate history (direct appeals, related proceedings)
- Treatment codes indicating how citing sources interpreted the authority (e.g., "followed," "distinguished," "overruled")
- Citing references organized by jurisdiction and source type
- Headnote analysis linking specific legal points in the original case to the citing references that discuss them
The headnote analysis is particularly useful. It lets you zero in on which citing cases discuss the specific legal point you care about, rather than forcing you to review every citing reference.
KeyCite System
KeyCite is Westlaw's answer to Shepard's. It performs the same basic function but uses a different set of visual indicators and integrates with Westlaw's broader research tools, including the West Key Number System.
West's Citation Checker
West Publishing launched KeyCite in 1997 as part of the Westlaw platform. It covers cases, statutes, regulations, and administrative decisions. Because it draws on West's extensive database, its coverage is comprehensive for U.S. legal materials.
Flags and Symbols
KeyCite uses a color-coded flag system to give you an at-a-glance status check:
- Red flag: The case is no longer good law for at least one point (overruled, reversed, or otherwise directly negated)
- Yellow flag: Some negative treatment exists, so proceed with caution (distinguished, criticized, or limited)
- Blue H: The case has direct history (appeals, related proceedings) but no negative treatment
- Green C: Other cases cite this authority, with no negative treatment indicated
- Q symbol: The authority's reasoning has been questioned by another court
A red flag doesn't always mean the entire case is bad. It might only affect one holding. You still need to read the citing case to understand what was negated.
Depth of Treatment Stars
KeyCite assigns star ratings to each citing reference to show how extensively it discusses your case:
- ★★★★ (four stars): Examined the cited case in depth
- ★★★ (three stars): Discussed the case substantially
- ★★ (two stars): Cited the case with some discussion
- ★ (one star): Mentioned the case briefly
These stars help you prioritize. If you're looking for cases that seriously engage with the legal reasoning of your authority, start with the four-star references.
Citation Analysis Process
Whether you're using Shepard's or KeyCite, the basic process follows the same steps.
Locating the Citation
- Identify the full citation of the authority you need to check (reporter, volume, and page number).
- Enter the citation into the Shepard's or KeyCite search field.
- Double-check that you've entered it correctly. A wrong volume or page number will pull up the wrong case or return no results.
- If parallel citations exist (e.g., both an official and unofficial reporter cite), use whichever the platform prefers, though both systems can usually resolve either.
Reading Treatment Codes
Each citation service uses standardized codes or labels to describe how a citing case treated your authority. Common treatments include:
- Followed: The citing court adopted the same reasoning
- Distinguished: The citing court found the case inapplicable due to factual or legal differences
- Criticized: The citing court disagreed with the reasoning but didn't overrule it
- Overruled: A higher court explicitly rejected the holding
Focus first on negative treatments. A case that has been "followed" dozens of times but "overruled" once on a key point may no longer support your argument.
Evaluating Subsequent History
Subsequent history is different from treatment. History tracks what happened to the same case on appeal, while treatment tracks what other cases said about it.
- Check whether the decision was affirmed, reversed, or vacated on appeal
- Look for remands that might have changed the outcome at the trial level
- Note any legislative action that codified or superseded the court's ruling
Positive vs. Negative Treatment
Not all citations are created equal. A case that has been cited 200 times might look authoritative, but if 15 of those citations are negative, you need to dig deeper.
Distinguishing Cases
When a court distinguishes a precedent, it acknowledges the case exists but finds it doesn't apply to the facts at hand. The court identifies specific factual or legal differences that justify reaching a different result. This doesn't invalidate the original case. It just limits where it applies. Still, if your case has been distinguished many times on the same point, that's a sign its reach may be narrower than you think.
Overruled Decisions
An overruled decision has been explicitly rejected by a higher court (or sometimes by the same court in a later decision). This is the most severe form of negative treatment. The overruled holding is no longer binding precedent in that jurisdiction.
That said, an overruled case might still have persuasive value in other jurisdictions that haven't addressed the issue, or it might be useful for historical context. But you should never cite an overruled case as binding authority without disclosing its status.
Questioned Authority
A questioned case falls between "followed" and "overruled." A court has expressed doubt about the reasoning or continued validity of the precedent without formally overruling it. This can signal that the law is shifting and the case may eventually be overruled. If you cite a questioned authority, acknowledge its limitations and consider whether stronger authority exists.
Citing References
Beyond checking validity, citation reports give you a window into how your authority fits within the broader legal landscape.
Related Cases
The list of citing cases shows every court that has referenced your authority. Look for:
- Cases with similar fact patterns that strengthen analogical reasoning
- Decisions from your jurisdiction that carry binding or strong persuasive weight
- Recent cases that may reflect the current state of the law more accurately
Secondary Sources
Citation reports also capture references in law review articles, treatises, and legal encyclopedias. These secondary sources can provide deeper analysis of the legal principles at stake, identify policy arguments, and point you toward additional primary authority you might have missed.
Statutes and Regulations
Sometimes a legislature responds to a court decision by enacting a statute that codifies, modifies, or overrides the ruling. Citation reports can flag these statutory references, helping you understand the interplay between judicial decisions and legislative action.
Updating Statutes and Regulations
Citation checking isn't just for cases. Statutes and regulations also need to be verified for current validity.
Legislative Changes
Statutes get amended, repealed, or replaced. When you cite a statute, confirm you're working with the current version by:
- Checking for recent amendments in the legislative session records
- Reviewing the effective dates of any changes
- Looking at any transitional provisions that affect how the amendment applies
Administrative Updates
Regulations can change through agency rulemaking. Monitor the Federal Register (for federal regulations) or state equivalents for proposed and final rules. Agency guidance documents and policy statements can also shift how a regulation is interpreted, even without a formal rule change.
Constitutional Challenges
A statute that's still "on the books" might be unenforceable if a court has struck it down on constitutional grounds. Check for pending or decided cases challenging the constitutionality of the statute you're citing, and note any legislative responses to those rulings.
Citation Checking Strategies
With potentially hundreds of citing references for a well-known case, you need strategies to work efficiently.
Narrowing Search Results
- Date restrictions: Focus on the most recent treatments to see the current state of the law.
- Keyword searches: Search within citing references for terms specific to your legal issue.
- Boolean operators: Use AND, OR, and NOT to refine results and filter out irrelevant references.
Filtering by Jurisdiction
Start with citing references from your jurisdiction, since those carry the most weight. Then expand to other jurisdictions to see how the authority has been received more broadly. Pay attention to whether there's a circuit split or disagreement among state courts on the issue.
Focusing on Relevant Treatments
- Prioritize negative treatments first to assess risk
- Use depth-of-treatment indicators (KeyCite stars or Shepard's analysis) to find cases that substantively engage with your authority
- Zero in on citing references that address the specific headnote or legal point relevant to your argument
Limitations of Citation Services
These tools are powerful, but they aren't perfect. Knowing their weaknesses helps you compensate.
Coverage Gaps
- Older cases or decisions from smaller jurisdictions may have incomplete coverage
- Unpublished opinions and some administrative decisions may not appear in citation reports
- Secondary source coverage varies between platforms
- International and foreign law citations receive less comprehensive treatment
Timeliness of Updates
There's always a lag between when a court issues a decision and when it appears in a citation database. For time-sensitive matters, supplement your citation check by searching for very recent decisions directly. Print versions update even more slowly than online versions.
Interpretation Challenges
Automated classification systems sometimes get it wrong. A case coded as "distinguished" might actually be more critical than the label suggests, or a "followed" tag might refer to a different legal point than the one you care about. There's no substitute for reading the actual citing case to understand the context.
Alternative Citation Tools
Shepard's and KeyCite are the industry standards, but other tools can supplement your research.
Google Scholar
Google Scholar provides free access to many legal opinions and includes a "Cited by" feature that shows subsequent citations. It's useful for quick checks and for finding scholarly articles, but it lacks the treatment codes and analytical depth of Shepard's or KeyCite. Don't rely on it as your sole citation-checking tool.
Fastcase
Fastcase offers a more affordable research platform with citation analysis through its Authority Check feature and an Interactive Timeline tool that visually maps citation relationships. Coverage may be more limited than Lexis or Westlaw, but it's a solid option for budget-conscious practitioners.
Bloomberg Law
Bloomberg Law includes BCite, its citation analysis tool, which provides treatment indicators and depth-of-discussion metrics for cases. Its Smart Code feature handles citation checking for statutes and regulations. Bloomberg also offers unique analytics tools for assessing the influence of cited authorities.
Integrating Citation Checking
Citation checking shouldn't be a last-minute task. Build it into your workflow from the start.
Legal Research Workflow
- Run preliminary citation checks on key authorities early in your research to avoid investing time in bad law.
- Update your checks periodically as research progresses, since new decisions can appear at any time.
- Use citing references as a research tool to discover related cases and expand your analysis.
- Track the status of each authority in your research notes so you don't lose track.
Writing Memoranda
Before finalizing any memorandum or brief, run a final citation check on every authority you cite. If a case has received negative treatment, address it directly in your analysis rather than hoping no one notices. Highlighting positive treatment (e.g., "widely followed across six circuits") can strengthen your argument.
Preparing for Oral Arguments
Review citation checks for all key authorities before oral argument. Opposing counsel or the judge may raise negative treatment you haven't addressed. Prepare explanations for any weaknesses, and have backup authorities ready. Check whether the specific court or judge you're appearing before has previously cited or discussed your key cases.