How to find cases with similar facts - a case-matching method for US attorneys
By LegiMatch Research Team · Published October 14, 2026 · Updated October 17, 2026 · 4 min read
Short answer: start by writing your facts as a neutral two-paragraph summary, pull out the legal issues and statutes, then combine (1) a fact-based search, (2) a targeted keyword search, and (3) the citation trail of the best results. AI "fact-pattern" search tools speed up the first step; citation trails and careful reading are still what confirm a case is on point.
Why matching facts is harder than matching words
Two decisions can describe the same situation in completely different words. A customer "slipped on water in the produce aisle" and a shopper "fell on a liquid near the store entrance" are the same premises-liability story, but a keyword search for one may miss the other. Courts also bury the facts that matter in the middle of long opinions, after procedural history.
That's why experienced researchers don't rely on a single search. They combine methods that fail in different ways.
Five ways to find factually similar cases
| Method | Best for | Main weakness |
|---|---|---|
| Keyword / terms and connectors | Distinctive words ("chain-link fence", "forklift") and exact phrases | Misses cases that describe the same facts differently |
| Digest topics or key numbers (Westlaw, Lexis) | Browsing all cases on a point of law | Organized by legal issue, not by facts; subscription needed |
| Citation trails (cases cited by and citing a good case) | Finding the cases courts themselves treat as related | Only as good as your starting case |
| Secondary sources (treatises, annotations) | Collected examples of fact patterns | Can be out of date; often paywalled |
| AI fact-pattern search | Matching the story in your matter, whatever the wording | Must be checked: you still need to read the decisions |
A step-by-step workflow
1. Write a neutral fact summary
Two short paragraphs: who, what happened, what harm, what the other side argues. Leave out client names and anything confidential the tool doesn't need. A good summary is the single biggest factor in search quality, for people and for AI tools.
2. List the legal issues and statutes
Name the claims and defenses in plain terms ("premises liability", "constructive notice", "summary judgment") and any statute you rely on, using its standard citation. Searching by issue and statute catches cases with different facts that decide the same question.
3. Run a fact-based search
Paste the summary into a tool that searches by meaning rather than exact words. Look at the top 10 to 20 results and note which share your material facts, the facts the court relied on, not just the topic.
4. Run two or three targeted keyword searches
Use the distinctive words from the best results. Terms and connectors help here: slip! /p (water OR liquid) /p "warning sign" finds paragraphs that mention all three ideas together.
5. Follow the citation trail
For the two or three strongest cases, check the cases they rely on and the later cases that cite them. Courts cite factually similar precedent when they compare facts, so this often surfaces the best matches.
6. Check that each case is still good law
Before relying on any decision, confirm it hasn't been reversed or overruled, and read how later courts treated it. A citator flag is a starting point, not a substitute for reading.
7. Read the decisions
Read the facts section and the reasoning of every case you plan to cite. Similarity scores, summaries and AI explanations help you prioritize; they don't replace reading.
How AI fact-pattern search fits in
AI tools that match facts work by turning your description and each decision into a mathematical representation of meaning, then ranking decisions whose facts and issues are closest to yours. Good tools add keyword and statute matching, and show you why a case ranked.
What to look for:
- Only real decisions, linked to the source. The tool should return decisions from a database, not generate citations.
- An explanation of the match, ideally broken down (facts, legal issues, statutes, jurisdiction, date).
- Jurisdiction filters, so binding authority isn't buried under persuasive cases from elsewhere.
- Outcomes shown up front, so you can separate favorable from unfavorable cases quickly.
LegiMatch was built around this workflow: you paste or upload your matter, review the issues it finds, and get similar US decisions ranked by a match score you can inspect. It's one step in the process above, not the whole process.
Frequently asked questions
Can I search case law by facts instead of keywords?
Yes. Fact-pattern (semantic) search tools compare the meaning of your description with the facts of each decision, so they can find cases that use different words. Combine them with keyword searches and citation trails for the best coverage.
How many similar cases should I review?
For most motions, reviewing the top 15 to 25 results from two or three different searches, then following the citation trail of the best three or four, gives good coverage. Stop when new searches keep returning cases you've already seen.
Are AI case-matching results reliable?
They're a fast way to find candidates, not a final answer. Treat the results as leads: read each decision, confirm it's still good law, and check the pinpoint quotes yourself before citing anything.
Do I need Westlaw or Lexis to find similar cases?
Not always. Free sources such as CourtListener and Google Scholar, plus lower-cost AI tools, cover a large share of published US decisions. Comprehensive citators, headnotes and secondary sources remain strengths of the large platforms.
Sources
- Caselaw Access Project, Harvard Law School Library: public-domain US case law (case.law)
- CourtListener, Free Law Project: US court opinions and citation network (courtlistener.com)
This article is general information about legal research, not legal advice. Verify every authority before relying on it.
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