Compared
Eight tools, read from their own pages on 2026-09-21; the Westlaw rows were re-read on 2026-09-24. Start with your situation. The free checkers have their own comparison.
Paste it here. Invented cases, wrong volumes and misquotes come back in seconds with the evidence, free for the first twenty checks, nothing stored. Turn on the deep check for the mistake an existence check cannot see: a real case cited for something it does not say. BriefCatch does a similar sweep inside Word for $60 a seat on an annual plan.
Use what you have for quotations and good law: Quick Check and KeyCite, or Brief Analysis and Shepard's. On Westlaw Advantage, Litigation Document Analyzer also looks for misstatements of law, and both Westlaw tools have a mode for the other side's brief. None of them publishes how often it is wrong. Keep them for the citator; paste the draft here for a second check whose error rates are on the table.
That question is called "is it still good law", and it is a citator's job: KeyCite on Westlaw, or Shepard's on Lexis. Nothing else on this page answers it, ours included. We check that the case exists, that you quoted it correctly, and that it says what you cite it for; whether a later court has since overruled or limited it is a different question.
Clearbrief scores how well each sentence relates to the page it cites, without a language model, for $300 a user a month. BriefCatch flags the same errors we do inside Word. Ours gives you a .docx back with a comment on every flagged citation.
Ours has an API and an open-source MCP server for Claude, Cursor and the OpenAI Agents SDK; an agent can open its own account. None of the other vendors' pages offers either.
CourtListener's citation lookup and Google Scholar answer "does this case exist", one citation at a time on their web pages. Several free checkers run a whole draft against CourtListener. Our free tier does that too, plus quotations, and needs no account. The free checkers compared.
Only here. BGE, BGer dockets, the federal courts and the 26 cantons; the report comes back in German, French or Italian. No other tool on this page mentions Swiss decisions.
| tool | case exists | quotation | says what you cite it for | still good law | error rate published | text kept | price |
|---|---|---|---|---|---|---|---|
| proofread.law | yes | yes | yes, opt-in | no | yes | no | free, then $0.50 a check or $29 a month |
| Westlaw Quick Check | yes | yes | not stated | KeyCite | no | not stated | with Westlaw, by quote |
| Westlaw Litigation Document Analyzer | yes | yes | yes, "misstatements of law" | KeyCite | no | upload destroyed after the analysis; report deleted within 48 hours | with Westlaw Advantage, from $256.75 a month |
| Lexis Brief Analysis | yes | yes | not stated | Shepard's | no | purged after the session | with Lexis+, by quote |
| CoCounsel | yes | yes | yes | KeyCite | no | not for training | with Westlaw, by quote |
| Clearbrief | not stated | not stated | yes, a score | not stated | no | not for training | $300 a user a month |
| BriefCatch RealityCheck | yes | yes | yes | not stated | no | no | $60 a seat a month, annual |
| CourtListener, Scholar | by hand | no | no | no | no | not stated | free |
"Not stated": the vendor's pages do not say. "Yes" is the vendor's own claim; ours is measured: 89% of invented cases caught, 1.2% false flags, and, at the confidence the report shows, the deep check confirms 55.0% of good citations and marks a wrong passage as support for 4.5% of wrong pairs (67.7% and 11.3% at any confidence). That is why it is a review queue and not a verdict. Every number, with its sample and caveats.
On LePhantomCite, a public benchmark from Princeton, our default check's results by class sit beside the systems in the paper, with what it does not check.
Westlaw and Lexis are the citators; if "has this case been overruled" is the question, that is the answer. CoCounsel and Clearbrief are drafting tools that check citations on the way. BriefCatch is the closest to what we do, inside Word, on a seat licence. Among the tools on this page, we are the paste box: the fastest to try, the cheapest to start, the only one that publishes its error rates, and the only one with Swiss law and an agent interface. What we do not do is tell you whether a case has since been overruled.
Every row above comes from the vendor's own pages. What each one says, and when we read it:
Quick Check "will produce a report with recommendations for additional relevant authority, warnings for cited authority, an analysis of quotations", and can "Analyze your opponent's brief to view KeyCite information for their citations". The help pages for Westlaw Edge and Westlaw Precision say "Quick Check will verify your citations and quotations." No Thomson Reuters page we read says Quick Check was replaced or retired. Westlaw Advantage adds Litigation Document Analyzer: "Building on Quick Check, this advanced AI tool reviews entire documents to spot both inaccurate citations and broader misstatements of law." Its modes include "analyze an opponent's work". After the analysis "Westlaw Advantage destroys the copy you uploaded", and the report "is deleted from Westlaw Advantage servers within 48 hours." "Westlaw Advantage pricing starts at $256.75 per month for single-circuit coverage and $399.75 per month for all states and federal coverage." KeyCite: "verify that the cases you cite are still good law". No error rate is published.
legal.thomsonreuters.com/en/products/westlaw-edge/quick-check · thomsonreuters.com/en-us/help/westlaw-precision/tools/quick-check.html · legal.thomsonreuters.com/en/products/westlaw-advantage/features · thomsonreuters.com/en-us/help/westlaw-advantage/tools/access-litigation-document-analyzer.html · sales.legalsolutions.thomsonreuters.com, Westlaw Advantage plans and pricing · read 2026-09-24. Also read 2026-09-21: legal.thomsonreuters.com/en/insights/articles/introducing-quick-check, /en/products/westlaw/keycite, /en/insights/infographics/quick-check-data-security, /en/westlaw/plans-and-pricing.
Brief Analysis "extracts quotations from your document and verifies that each quote accurately matches the cited primary source, including whether the pin cites provided are correct". Protégé (renamed from Lexis+ AI in February 2026): "Shepard's Verify checks citations in AI responses, documents, and drafts", and, per the press release of 2026-05-07, "flags citations that cannot be verified as existing". On data: "No full document text is stored after the session ends"; "Delivered reports remain in History for 90 days"; "We never use customer data to train AI models". Pricing is by quote. No error rate is published.
supportcenter.lexisnexis.com answers 1123689, 1102034 and 1102030 · lexisnexis.com/en-us/products/lexis/shepards.page · lexisnexis.com/en-us/products/lexis-plus-ai.page · the LexisNexis press release of 2026-05-07 · read 2026-09-21
"every citation is linked so attorneys can click through and verify the work themselves"; "Citation checking, quote validation, and issue spotting are part of how Westlaw Brief Builder works"; Deep Research Verify is described as "checking that cited Westlaw and Practical Law authority actually supports each legal assertion". On data: "we never use it to train underlying models". No price is shown, and the pages do not say which plan carries the checks. No error rate is published; a commissioned survey measures perception, not errors.
legal.thomsonreuters.com/en/products/cocounsel · /en/products/cocounsel-legal/plans · /en/products/cocounsel-essentials · the Thomson Reuters blog post of 2026-08-21 at /blog/the-next-generation-of-cocounsel-legal/ · read 2026-09-21
Clearbrief "automatically detects every citation in a Word document to both facts and law" and "gives a score to measure how well your sentence relates to the cited page", with "patented technology that does not rely on generative AI". Its own pages do not say whether it checks that a case exists, the quotation, or good law. On data: "Your data is never used for training large language models"; SOC 2 Type 2. Price: "Solo $300 /month Per user per month". No error rate is published.
clearbrief.com · clearbrief.com/lexis-nexis · Clearbrief blog posts of 2026-06-07 and 2026-08-24 · read 2026-09-21
"RealityCheck verifies cited cases and federal statutes". The error types it lists include citations to cases that do not exist, quotations that do not match the source, incorrect pincites, cases cited for propositions they reject, and concurrences or dissents presented as majority holdings. It does not say which database it checks against, or whether it covers good law. On data: "BriefCatch never stores, retains, or uses your text or documents". Price: $60 a seat a month for an individual, billed annually; Pro $75, minimum 5 seats. No error rate is published.
briefcatch.com/realitycheck · briefcatch.com/pricing · briefcatch.com/trust-center · read 2026-09-21
CourtListener's lookup: "This tool is limited by the citations that we have in our system"; its API takes up to 64,000 characters and 250 citations per request. Google Scholar: "Google does not warrant that the information is complete or accurate." Neither is a checker in the sense of the rows above. Both are compared in detail with the free checkers.
courtlistener.com/c/ · scholar.google.com/intl/en/scholar/help.html · read 2026-09-24
If a vendor's page changes, tell us at hello@proofread.law and the row changes.