Citators

What Are Citators and Why They're Essential

A citator is a research tool that tracks the subsequent history and treatment of legal authorities. Citators tell you whether a case is still good law, how courts have interpreted it, and what other authorities have cited it. Using a citator is not optional—it is an essential step in every legal research project.

Before citators existed, lawyers had to manually search through subsequent cases to determine whether their authorities were still valid. This was time-consuming and error-prone. Modern electronic citators—KeyCite (Westlaw), Shepard's (Lexis), and BCite (Bloomberg Law)—automate this process and provide instant access to citing references.

What Citators Track

Citators provide several categories of information about legal authorities:

• Direct history — What happened to this specific case on appeal (affirmed, reversed, remanded, etc.)
• Negative treatment — Cases that have overruled, criticized, distinguished, or otherwise negatively treated your authority
• Positive treatment — Cases that have followed, explained, or cited your authority favorably
• Citing references — All authorities (cases, statutes, secondary sources) that have cited your authority
• Related authorities — Other materials on the same legal issues

Two Essential Purposes: Validation and Expansion

Citators serve two distinct but equally important functions in legal research. Understanding both will make you a more effective researcher.

Purpose 1: Validation (Is This Still Good Law?)

The primary purpose of using a citator is to verify that your authority is still valid. Before you rely on any case, statute, or regulation, you must confirm:

• For cases: Has the case been overruled, reversed, or superseded? Has it been criticized or distinguished on the points you're relying on?
• For statutes: Has the statute been amended, repealed, or held unconstitutional?
• For regulations: Has the regulation been amended, withdrawn, or invalidated?

Validation is defensive research—you're protecting yourself from relying on bad law. Even if a case has not been formally overruled, extensive negative treatment may indicate that courts are unlikely to follow it.

Purpose 2: Expansion (Finding More Authorities)

The second purpose of citators is to expand your research by finding additional relevant authorities. When you have one good case, a citator helps you find:

• Cases that cited your case — Later courts discussing the same legal issues
• Cases your case cited — Foundational authorities and earlier precedents
• Secondary sources — Treatises, law reviews, and practice materials discussing your case
• Related cases — Other authorities on similar legal points

Expansion is offensive research—you're using one good authority to find more. This is particularly valuable because citator results are organized by how they treat your authority, making it easy to find cases that support (or oppose) your position.

KeyCite (Westlaw)

KeyCite is Westlaw's citator service. It provides comprehensive citation information through a system of status flags, depth indicators, and filtering tools. Understanding how to read and use KeyCite is essential for Westlaw users.

KeyCite Status Flags

KeyCite uses colored flags to provide instant visual indicators of an authority's status. These flags appear next to case names throughout Westlaw.

Red Flag

A red flag is the most serious warning. It indicates that the case is no longer good law for at least one point of law. Red flags appear when:

• The case has been overruled or reversed on the relevant legal point
• A statute the case relied upon has been held unconstitutional or repealed
• The case has been superseded by statute

Action required: Do not cite a red-flagged case without carefully investigating the negative history. The flag may apply to only one holding in the case, so determine whether your specific proposition has been affected.

Yellow Flag

A yellow flag indicates that the case has received some negative treatment but has not been overruled or reversed. Yellow flags appear when:

• The case has been criticized by other courts
• The case has been distinguished on significant grounds
• The case's reasoning has been questioned
• The case has been limited to its specific facts

Action required: Review the negative treatment to understand its nature and scope. A yellow flag does not mean you cannot cite the case, but you should understand and potentially address the criticisms.

Blue-Striped Flag (H)

A blue-striped "H" flag indicates that the case has direct appellate history that is not negative. This includes:

• The case was affirmed on appeal
• Certiorari was granted or denied
• The case was remanded for reasons that don't affect the legal holding
• Related proceedings exist in the case's history

Action required: Review the history to understand the case's procedural posture, but this flag typically does not indicate problems with the case's validity.

Orange Flag (C)

An orange "C" flag indicates that the case has been cited in a related proceeding or has information about pending appeals. This is informational rather than a warning.

No Flag

The absence of a flag means KeyCite has found no direct history and no negative citing references. However, this does not guarantee the case is good law—it simply means no court has explicitly overruled or criticized it yet.

Depth of Treatment Stars

KeyCite uses a star system to indicate how extensively a citing case discusses your authority:

• Four stars (Examined) — The citing case contains an extended discussion of your case (typically a full paragraph or more)
• Three stars (Discussed) — The citing case contains a substantial discussion (more than a sentence but less than extended)
• Two stars (Cited) — The citing case contains some discussion of your case
• One star (Mentioned) — The citing case briefly mentions your case (often just a citation with little or no discussion)

When expanding research, prioritize four-star and three-star citations. These cases engage substantively with your authority and are more likely to provide useful analysis. One-star citations may just be string cites with minimal value.

KeyCite Sections and Tabs

KeyCite organizes information into several sections:

Negative Treatment

The Negative Treatment section appears at the top when your case has received any negative treatment. It lists:

• Cases that have overruled, reversed, or criticized your case
• The specific type of negative treatment (declined to follow, distinguished, criticized, etc.)
• Which headnotes were affected by the negative treatment

Always review this section first. Understanding how your case has been treated negatively is essential for responsible citation.

History

The History tab shows the direct procedural history of your case—what happened before and after the decision you're viewing. This includes appeals, remands, and related proceedings in the same litigation.

Citing References

The Citing References tab lists all authorities that have cited your case, organized by type (cases, administrative decisions, secondary sources, etc.). This is your primary tool for research expansion.

Table of Authorities

The Table of Authorities shows what authorities your case cited. This helps you trace legal principles back to their sources and find foundational cases.

Filtering KeyCite Results

KeyCite results can be filtered to focus your research:

• By headnote — See only citations to specific legal propositions
• By jurisdiction — Limit to your controlling jurisdiction or persuasive jurisdictions
• By date — Focus on recent decisions or a specific time period
• By treatment — Show only cases with specific types of treatment (followed, distinguished, etc.)
• By depth — Limit to citations with substantial discussion (three or four stars)
• By document type — Filter by cases, secondary sources, briefs, etc.

Interpreting KeyCite Results

When reviewing KeyCite results, follow this process:

1. Check the flag — Is there a red or yellow flag? If so, investigate immediately.
2. Review negative treatment — Understand any criticisms or limitations.
3. Check direct history — Know the case's procedural posture and appellate history.
4. Filter citing references — Focus on relevant headnotes, your jurisdiction, and substantial discussions.
5. Review key citations — Read the most important citing cases to understand how your authority has been applied.

Shepard's (Lexis)

Shepard's Citations is the citator service on Lexis, with a history dating back to the 1870s. While it serves the same fundamental purposes as KeyCite, Shepard's uses different signals and organizational approaches.

Shepard's Signals

Shepard's uses colored shapes as signals to indicate a case's status:

Red Stop Sign

A red stop sign is Shepard's most severe warning. It indicates strong negative history or treatment:

• The case has been overruled by a subsequent case
• The case has been reversed or vacated
• The case has been superseded by statute

Action required: Investigate immediately. Determine whether the negative history affects the specific holding you want to cite.

Red Exclamation Point

A red exclamation point indicates that the case has negative treatment that is not as severe as overruling:

• The case has been criticized
• A court has declined to follow the case
• The case has been questioned

Yellow Triangle

A yellow triangle indicates caution—the case has some negative treatment or history that may affect its validity:

• The case has been distinguished by subsequent courts
• The case has been limited to its facts
• The case has received mixed treatment
• There is pending appellate action

Action required: Review the treatment to understand its nature. Distinguish and limited treatment may not prevent citation but should be acknowledged.

Green Diamond (Plus Sign)

A green diamond with a plus sign indicates positive treatment:

• The case has been followed by other courts
• The case has been affirmed on appeal

This is a favorable indicator, but remember that even cases with positive treatment can have specific holdings that have been criticized.

Blue Circle (A)

A blue circle with "A" indicates that citing references are available but there is no direct history or significant treatment. The case has been cited but not evaluated positively or negatively.

Orange Square (Q)

An orange square with "Q" indicates the case's validity has been questioned by dicta or in a concurrence or dissent, but not in a holding.

Shepard's Analysis Categories

Shepard's categorizes the treatment of your case using specific analytical labels:

Positive Analysis

• Followed — The citing case explicitly follows your case's holding
• Affirmed — Your case was affirmed on appeal
• Explained — The citing case interprets or clarifies your case's holding

Neutral/Cautionary Analysis

• Distinguished — The citing case finds factual or legal differences that lead to a different result
• Harmonized — The citing case reconciles apparent inconsistencies with your case
• Cited by — Your case is cited without specific analysis

Negative Analysis

• Overruled — Your case's holding has been explicitly overruled
• Superseded — Your case has been superseded by statute or rule
• Criticized — The citing case disagrees with your case's reasoning
• Questioned — The citing case raises doubts about your case's continued validity
• Limited — The citing case restricts your case to its specific facts
• Declined to follow — The citing case refuses to apply your case's reasoning

Shepard's Headnote Filtering

Like KeyCite, Shepard's allows you to filter citing references by headnote. This is crucial because:

• A case may be cited for many different propositions
• Negative treatment may apply only to certain headnotes
• You can focus research on citations to your specific legal issue

To filter by headnote in Shepard's:

1. Open the Shepard's report for your case
2. Look for the headnote filter in the left sidebar or top filter bar
3. Select the headnote numbers corresponding to your legal issue
4. The citing references will update to show only citations to those propositions

Interpreting Shepard's Results

When reviewing a Shepard's report:

1. Note the signal — Red signals require immediate investigation; yellow signals require review.
2. Check the Appellate History section — Understand the case's direct procedural history.
3. Review the Citing Decisions section — Focus on cases with strong analysis categories (followed, criticized, distinguished).
4. Use filters — Narrow by jurisdiction, date, headnote, and analysis type.
5. Sort strategically — Sort by court hierarchy, date, or depth of discussion depending on your needs.

BCite (Bloomberg Law)

BCite is Bloomberg Law's citator service. While less widely used than KeyCite or Shepard's, it provides useful citator functionality for Bloomberg Law subscribers.

BCite Indicators

BCite uses a simpler signal system:

• Red indicator — The case has direct negative history (reversed, overruled, vacated)
• Orange indicator — The case has been distinguished or has received some negative treatment
• Green indicator — The case has only positive or neutral treatment

BCite Analysis

BCite provides analysis categories similar to KeyCite and Shepard's, including:

• Direct history (affirmed, reversed, remanded, etc.)
• Case analysis (distinguished, followed, criticized, etc.)
• Citing references organized by type and jurisdiction

BCite Strengths and Limitations

Strengths:

• Integrated with Bloomberg Law's interface
• Includes citations from court filings and dockets
• Clean, streamlined interface

Limitations:

• Smaller market share means fewer users and less feedback
• Editorial analysis may be less comprehensive than KeyCite or Shepard's
• Fewer filtering options than competitors

If your primary research platform is Bloomberg Law, BCite is a serviceable citator. However, for comprehensive validation, many practitioners still verify results with KeyCite or Shepard's.

KeyCite vs. Shepard's: Comparison

Both KeyCite and Shepard's are comprehensive citator services. Understanding their similarities and differences helps you use each effectively.

Key Differences

• Visual signals: KeyCite uses flags; Shepard's uses shapes. Both convey similar information but require learning different visual cues.
• Depth indicators: KeyCite's star system provides a quick visual reference for discussion depth. Shepard's uses different indicators.
• Positive treatment signals: Shepard's explicitly signals positive treatment with a green diamond. KeyCite has no equivalent positive flag—you must look at the actual treatment.
• Analysis categories: Both use similar categories, but terminology differs slightly (e.g., "declined to extend" vs. "declined to follow").
• Integration: Each citator integrates with its platform's other features (KeyCite with Key Numbers; Shepard's with Lexis headnotes).

Why You Should Check Both Citators

Research consistently shows that KeyCite and Shepard's can produce different results for the same case. This happens because:

• Different editorial decisions: Human editors at each company may categorize treatment differently (e.g., one may call it "criticized" while the other calls it "distinguished")
• Different timing: One citator may process new citations faster than the other
• Different coverage: Each may include different secondary sources and court filings
• Different algorithms: Automated processes for identifying citations may vary

When to Check Both

At minimum, check both citators for:

• Key cases — Any case that is central to your legal argument
• Old cases — Cases more than 10-15 years old that may have more citing history
• Cases with flags — If either citator shows negative treatment, check the other
• Appellate briefs — Every case cited in a brief filed with an appellate court
• Uncertain results — When one citator's results seem incomplete or ambiguous

When One Citator May Suffice

For routine research, a single citator is often adequate:

• Recent cases with limited citing history
• Cases with no flags or signals in the citator you're using
• Cases that are secondary to your argument (cited for background propositions)
• Initial research stages where you're surveying the landscape

Cite-Checking Statutes and Regulations

Citators are not just for cases. Both KeyCite and Shepard's provide citator services for statutes and regulations, which is essential for statutory and regulatory research.

Why Cite-Check Statutes

Statutes change. Before relying on any statutory provision, you must verify:

• Current status: Has the statute been amended, repealed, or renumbered?
• Constitutional validity: Has any court held the statute unconstitutional?
• Judicial interpretation: How have courts interpreted key provisions?
• Effective dates: What version of the statute applies to your situation?

KeyCite for Statutes

KeyCite for statutes provides:

• Status flags: Red flags indicate the statute has been amended, repealed, or held unconstitutional; yellow flags indicate proposed legislation or partial amendments
• History: Legislative history showing when the statute was enacted and amended
• Citing references: Cases, regulations, and secondary sources that cite the statute
• Validity indicators: Information about constitutional challenges

Important: Read the Notes

When KeyCite flags a statute, click through to read the specific notes. A flag might indicate that one subsection was amended while others remain unchanged. Understanding exactly what changed is crucial.

Shepard's for Statutes

Shepard's statutory citator provides similar functionality:

• Signals: Red signals for statutes held unconstitutional; yellow signals for amendments or validity questions
• Citing decisions: Cases that have interpreted or applied the statute
• Subsection analysis: Treatment of specific subsections
• Secondary sources: Law reviews and treatises discussing the statute

Cite-Checking Regulations

Regulations require the same verification as statutes:

• Current status: Has the regulation been amended or withdrawn?
• Validity: Has any court invalidated the regulation as exceeding agency authority or being arbitrary and capricious?
• Interpretation: How have courts and agencies interpreted the regulation?

Both KeyCite and Shepard's cover the Code of Federal Regulations. Check for:

• Federal Register citations: Recent amendments or proposed rules
• Court decisions: Cases challenging or interpreting the regulation
• Agency guidance: Interpretive rules and guidance documents

Statutory Annotations vs. Citator Results

Remember that statutory annotations (Notes of Decisions in U.S.C.A., Case Notes in U.S.C.S.) and citator results overlap but serve different purposes:

• Annotations: Comprehensive summaries of all cases interpreting the statute, organized by topic
• Citator: Focus on the statute's validity and treatment, with less detailed case analysis

Use annotations to understand how a statute has been interpreted. Use the citator to verify the statute is still valid and to find the most recent citing references.

Common Mistakes to Avoid

Even experienced researchers make citator mistakes. Avoid these common errors:

Mistake 1: Relying Solely on the Flag/Signal

The problem: Seeing no red flag and assuming the case is definitely good law, or seeing a red flag and assuming the entire case is bad.

The solution: Always investigate the underlying treatment. A red flag might only affect one holding. A case with no flag might have been effectively undermined by changes in legal doctrine not captured by the citator.

Mistake 2: Ignoring Headnote Specificity

The problem: Failing to check which specific holdings have been negatively treated. You might cite a case for Proposition A when only Proposition B has been overruled.

The solution: When a case has negative treatment, always check which headnotes are affected. Ensure the specific proposition you're citing remains valid.

Mistake 3: Not Filtering Results

The problem: Wading through hundreds of citing references without filtering, missing relevant cases, and wasting time on irrelevant ones.

The solution: Use filters aggressively. Filter by headnote, jurisdiction, date, and depth of treatment. Focus your review on the most relevant citations.

Mistake 4: Checking Only Cases

The problem: Cite-checking cases but forgetting to verify statutes and regulations.

The solution: Every authority needs verification. Statutes can be amended or held unconstitutional. Regulations can be withdrawn or invalidated. Make citation verification a habit for all authority types.

Mistake 5: Using Only One Citator

The problem: Relying exclusively on KeyCite or Shepard's when the other might reveal different treatment.

The solution: For important authorities, check both citators. This is especially critical for cases central to your argument or when preparing appellate briefs.

Mistake 6: Citing Without Current Verification

The problem: Cite-checking during research but not re-checking before filing. Cases can receive negative treatment between research and submission.

The solution: Always re-verify your key authorities immediately before filing any document. This final check catches recent developments.

Mistake 7: Misunderstanding "Distinguished"

The problem: Treating "distinguished" as negative treatment when it may not be. Courts distinguish cases constantly without undermining their validity.

The solution: Read the distinguishing case. A case can be distinguished on facts without criticizing the legal rule. Distinguish is often neutral, not negative.

Practical Tips for Effective Citator Use

Build Citator Checks into Your Workflow

Don't treat citation verification as a separate step at the end of research. Instead:

• Check each case as you find it during research
• Use citator expansion (citing references) as a research tool, not just validation
• Note flags and treatment in your research notes
• Create a final verification checklist for all cited authorities

Use Citators for Research Expansion

Remember that citators are powerful research tools, not just validation tools:

• Find later cases that follow or develop your authority's reasoning
• Identify cases that distinguish your authority (useful for anticipating counterarguments)
• Discover secondary sources discussing your case
• Trace legal principles backward through the table of authorities

Document Your Verification

Keep a record of your citator checks:

• Note the date you checked each authority
• Record which citator(s) you used
• Document any flags or treatment you investigated
• This protects you if questions arise later about your research diligence

Next Steps

Now that you understand citators, continue building your verification and citation skills:

• Citation (Bluebook) — Learn proper citation format for legal authorities
• Case Law Research — Master techniques for finding cases to cite-check
• Statutory Research — Understand statutory research and verification
• Platform Comparison — Compare Westlaw, Lexis, and Bloomberg Law features