A headnote is a short, editor-written summary of a single legal point decided in a court opinion, placed at the top of the published case before the full text begins. Legal publishers like Westlaw and LexisNexis create them as research aids, which means a headnote carries no legal authority and cannot be cited as precedent. Its job is to help you scan a decision’s key issues, jump to the exact passage where each issue is discussed, and find other cases on the same question.
Who Writes Headnotes
Courts don’t write headnotes. When an opinion is published, attorney-editors at the legal publishers read it and draft a separate summary for each legal issue the court addressed. At Westlaw, owned by Thomson Reuters, those editors are bar-admitted attorneys who condense each point of law into a concise, usually one-sentence statement. LexisNexis uses its own editorial staff and a similar process. A single case typically produces several headnotes because most opinions resolve more than one issue.
Because headnotes are editorial products rather than judicial work, they sometimes oversimplify or slightly mischaracterize what the court actually held. That gap is why no court treats a headnote as authoritative. Think of them the way you’d treat a book’s table of contents: useful for orientation, never a substitute for reading the chapter.
What a Headnote Contains
Formats vary between publishers, but most headnotes share the same parts:
- A numbered identifier like [1], [2], or [3] that corresponds to a bracketed marker inside the full opinion. Clicking the number jumps you to the passage where the court discusses that issue.
- A topic and classification tag. On Westlaw, this is a Topic and Key Number. On LexisNexis, headnotes carry word-based topic and subtopic labels.
- A short summary of the legal point, often with enough factual context to show how the court reached its conclusion.
- Cross-references to related statutes, regulations, or secondary sources, so you can move from the case to the underlying law without starting a new search.
How to Use Headnotes in Research
Triage first. When a search returns dozens of cases, reading each opinion end to end is impractical. Headnotes let you skim the key issues in seconds and decide whether a case is worth a full read. That’s where most of the time savings come from.
Once you find a relevant headnote, it doubles as a navigation tool. The numbered identifier links straight to the matching passage in the opinion, so you skip past procedural history and background and land on the analysis you actually need.1LibGuides at American University Washington College of Law. Headnotes and the Key Number System
Headnotes also widen your search. Because each one carries a subject classification, you can follow that tag to every other case in the system tagged with the same issue. One good case becomes a doorway to dozens more, across jurisdictions, without writing a single new keyword query.
The West Key Number System
Westlaw’s Key Number System is the most widely used classification scheme for headnotes. It dates to the 19th century and organizes American case law into more than 400 broad topics, each divided into increasingly specific subtopics and individual key numbers. The system contains more than 100,000 specific key numbers, and the hierarchy can run up to eight levels deep.2Thomson Reuters. Efficient Legal Research: Why You Need the West Key Number System
Key numbers stay consistent across all Westlaw products and jurisdictions. A key number you find in a federal case will pull up state cases on the identical issue, and the reverse. Every headnote in the system is filed under its key number, so following that number produces a curated set of cases analyzing the same point of law.
How LexisNexis Handles Headnotes Differently
LexisNexis uses words instead of numbers. Its headnotes are tagged with descriptive topic and subtopic labels rather than numerical codes. Within a case, LexisNexis assigns simple identifiers like HN1, HN2, and HN3 that link to related cases on the same topic. The approach works well for following a thread inside one case, but it lacks the universal numerical taxonomy that makes Westlaw’s key numbers portable across jurisdictions.
Researchers who use both platforms tend to treat them as complementary. Westlaw’s numbering suits systematic topic-driven browsing. LexisNexis’s word-based tagging feels more intuitive for people who prefer searching by concept. Neither is objectively better; it depends on how you think about legal problems.
Headnotes vs. a Court’s Own Syllabus
The U.S. Supreme Court adds its own summary to the front of each opinion, called a syllabus. The Reporter of Decisions prepares it, not an outside publisher, and it reads much like a headnote. Even so, the syllabus “constitutes no part of the opinion of the Court” and exists solely “for the convenience of the reader.”3Legal Information Institute (LII) / Cornell Law School. United States v. Castillo, 528 U.S. 320 That disclaimer dates back to a 1906 case, United States v. Detroit Timber & Lumber Co., in which the justices found that a headnote in an earlier decision had misstated the court’s holding.
Ohio is a notable exception. Under the Ohio Supreme Court’s Rules for the Reporting of Opinions, “the law stated in an opinion of the Supreme Court shall be contained in its text, including its syllabus, if one is provided.” The same rules say any introductory material other than the syllabus is a “research and indexing aid” and does not control.4Supreme Court of Ohio. Supreme Court Rules for the Reporting of Opinions So in Ohio, the court’s own syllabus carries legal weight. Publisher-created headnotes remain non-authoritative everywhere.
Why You Should Never Cite a Headnote
This is the single most important rule: a headnote is not the law. It’s one editor’s interpretation of what a court said, and editors sometimes get it wrong. The 1906 Supreme Court decision that gave rise to the syllabus disclaimer exists because a headnote misrepresented a holding and someone relied on it.
Citing a headnote instead of the opinion signals to a court that you either didn’t read the case or don’t understand the difference between editorial material and judicial authority. Under Federal Rule of Civil Procedure 11, attorneys certify that their legal contentions are “warranted by existing law” when they sign and file a pleading. An argument resting on a headnote rather than the court’s actual language can fall short of that standard, and courts have discretion to impose sanctions for Rule 11 violations, including monetary penalties and orders to pay the opposing party’s attorney fees.5Legal Information Institute (LII) / Cornell Law School. Federal Rules of Civil Procedure Rule 11 – Signing Pleadings, Motions, and Other Papers; Representations to the Court; Sanctions
The workflow is simple. Use headnotes to find relevant cases and locate the right passages. Then read and cite the opinion itself. The headnote gets you to the door; the opinion is what you walk through.
Free Alternatives if You Don’t Have Westlaw or Lexis
Westlaw and LexisNexis are expensive, and not everyone has institutional access. Several free resources offer some of the same research benefits, though none replicate the full editorial headnote experience.
- CourtListener, from the Free Law Project, provides judge-written summaries called “parentheticals” that distill the reasoning behind cited cases, grouped by theme. Copyrighted publisher headnotes are redacted, but the parentheticals serve a similar orientation function.6Free Law Project. A Faster, Smarter, Unified Case Law Experience
- Google Scholar offers free case law access with a basic “Cited By” feature showing which later cases reference a given decision. It has no formal headnotes, but the citation tracking helps you build a research trail.
- Justia publishes case law with editorial summaries on some decisions, useful as a starting point before moving to a commercial platform.
- The Caselaw Access Project, a Harvard Law School initiative, digitized millions of cases and made them freely available. The collection includes the full text of opinions but not publisher-created headnotes.7Harvard Law School. Caselaw Access Project Conference Marks Full Release of Digitized Decisions
None of these free tools offer anything like West’s key number classification for systematic topic research. But for reading the opinion itself and tracing its citations, they’re enough.