CoCounsel vs Lexis+ AI (2026): Which Is Better for a Small Firm?

CoCounsel vs Lexis+ AI comes down to the research database you already pay for. CoCounsel is Thomson Reuters' AI, and its case-law research runs on Westlaw. Lexis+ AI, renamed Lexis+ with Protégé in February 2026, runs on LexisNexis content and Shepard's. A Westlaw shop should pick CoCounsel; a Lexis shop should pick Protégé. We found no independent benchmark that tests the current versions against each other.

If your firm pays for neither, skip to the third-option section below.

CoCounsel vs Lexis+ AI at a glance

Prices and features as of September 2026; sources linked below.

Sources: CoCounsel plans, Westlaw Advantage pricing, CoCounsel Legal pricing, LawSites on CoCounsel integrations, Lexis+ with Protégé, LexisNexis store, CaseRead pricing.

What are CoCounsel and Lexis+ AI called now?

Both brands changed in the past year. Lexis+ AI is now Lexis+ with Protégé, and CoCounsel is four Thomson Reuters plans, two of which include Westlaw research.

LexisNexis's product page says it directly: "Lexis+ AI was renamed Lexis+ with Protégé in February 2026," and anyone who used Lexis+ AI now has access to the new platform. The general-availability announcement calls it the "integrated flagship platform that replaces Lexis+ AI," launched with more than 300 workflows. Per the LexisNexis store, "Lexis+ with Protégé includes all of Lexis+ and integrates generative AI": you buy the platform and the AI together.

Thomson Reuters sells CoCounsel as four plans: CoCounsel Essentials, Westlaw Advantage with CoCounsel Essentials, Practical Law Dynamic Tool Set with CoCounsel Essentials, and CoCounsel Legal, which bundles all three. On August 20, 2026, the company released the next generation of CoCounsel Legal, a fully agentic version that works from Westlaw, Practical Law and your own documents and adds Westlaw Brief Builder.

Does CoCounsel require Westlaw? For research, yes. Essentials is sold without Westlaw, but it is a document and drafting tool (tabular analysis, clause drafting, contract playbooks, deposition prep). Lawyerist's CoCounsel review lists "Not for Caselaw Research" among the cons. AI research over case law lives in the two plans that include Westlaw Advantage. One stale-data warning: some third-party pricing pages still quote a "CoCounsel Core" plan. Thomson Reuters' current plans page lists no plan by that name.

How much do CoCounsel and Lexis+ with Protégé cost?

Neither vendor lists a price for its AI bundle. Thomson Reuters does publish Westlaw Advantage prices; LexisNexis publishes no figure.

• Westlaw Advantage starts at $256.75 per month for single-circuit coverage and $399.75 for all states and federal, with Deep Research and KeyCite included. Online pricing is for new customers at firms of up to 10 attorneys; two-year terms save 12% and three-year terms 18%.
• Adding CoCounsel Essentials moves you to a configurator quote. Third-party tracking at CostBench pulled one on June 9, 2026: a solo attorney with all-states-and-federal coverage was quoted $639.20 per user per month on a one-year term for Westlaw Advantage with CoCounsel Essentials, or $519.35 on three years. That is one configuration on one date.
• Lexis+ with Protégé pricing, per LexisNexis, "varies based on factors such as the size of your organization, specific capabilities required, and the scope of content access." The store routes buyers to 1-888-AT-LEXIS, and Lawyerist's review lists "No Published Pricing" as a con.

On transparency, Thomson Reuters is ahead: a solo can see a real Westlaw number before talking to anyone. More on the configurator in our CoCounsel alternatives guide; what to get in writing from Lexis is in our Lexis+ Protégé review.

Which is more accurate, CoCounsel or Lexis+ AI?

We found no independent test of the current versions side by side. Every benchmark cited online is older or missing one of them.

• Stanford RegLab, May 2024. The most recent independent study we found that tested both vendors' research AI. Lexis+ AI answered 65% of queries accurately and hallucinated 17% of the time, against 42% and 33% for Westlaw AI-Assisted Research, per LawSites. It did not test CoCounsel, and Lexis+ AI has since become Lexis+ with Protégé.
• Vals Legal AI Report, February 2025. CoCounsel scored between 73.2% and 89.6% on four document tasks, including the top score for document summarization. LexisNexis withdrew, telling Artificial Lawyer that its Protégé upgrade "rendered the benchmarking analysis out-of-date and inaccurate." These were document tasks, not case-law research.
• Vals legal research benchmark, October 2025. Neither took part; spokespeople for both companies said they did not opt in.

Any page declaring one incumbent "more accurate" is extrapolating from a 2024 study of products that have changed since. Test both on a question you have already researched.

KeyCite vs Shepard's: does the citator decide it?

For most firms, yes. The citator is the strongest reason to buy either product, and the one your team reads fluently is the one to keep.

KeyCite flags negative treatment and adds Overruling Risk, which Thomson Reuters says warns when a point of law "has been implicitly undermined" by reliance on an overruled decision. Shepard's provides what LexisNexis calls "comprehensive editorial analysis" of case law, with treatment signals attached to individual headnotes. Our Westlaw vs LexisNexis comparison covers the flag systems; how to Shepardize a case covers the method.

Each vendor has also pointed its citator at AI output. Westlaw's Litigation Document Analyzer "reviews entire documents to spot both inaccurate citations and broader misstatements of law," including opposing arguments, and Thomson Reuters' August 2026 release describes Deep Research Verify, which "checks whether cited Westlaw and Practical Law authority supports specific legal assertions." LexisNexis says Shepard's Verify checks citations in AI responses, documents and drafts and flags unsupported statements; at its May 2026 launch, LawSites read the description as confirming only that authority "exists and is retrievable." In a demo, hand each one a brief with a known bad citation.

CoCounsel vs Lexis+ AI: which is better for a small firm?

The one that matches your database. Switching platforms for a different AI assistant usually costs more in retraining than either AI layer is worth.

CoCounsel's strength is document work: Essentials covers contract playbooks, deposition prep and tabular review, and CoCounsel Legal adds Practical Law. Lawyerist rates it 4.6 out of 5. Lexis+ with Protégé offers model choice (its General AI mode includes models from OpenAI, Google and Anthropic), plus Practical Guidance in 25 practice areas and a 2-day free trial. Lawyerist rates it 4.3 out of 5. Both vendors say customer data is not used to train their AI.

The third option for a 1–10 lawyer firm

Full disclosure: CaseRead is our product.

Both incumbents are AI layers on a research subscription, so for a firm on neither, the price floor is the database underneath. CaseRead has no base-database subscription. The published pricing: a free plan with no card (20 research questions a month, up to 4 a day, and 2 citation checks a day), Solo at $149 a month ($119 billed annually), and Team at $199 per seat ($159 annually), month-to-month, with a 7-day trial on paid plans.

What it does differently:

• Searches your own case files and public law in one query. Connect Google Drive or OneDrive, or use the built-in vault, and research runs against one matter's documents, parties and jurisdiction together with public law. No document-management system is needed.
• Grounded or flagged. Every citation links to the source it was retrieved from. Anything CaseRead can't ground in a retrieved source is flagged rather than asserted.
• Free citation checks on any brief. The Hallucination Shield is free and public. Paste text or upload a file (scans are OCR'd), including opposing counsel's brief, and each citation gets two checks: does the source exist, and does it support the claim. Up to 50 citations per run.
• Per-firm isolation. Each firm's vault lives in its own database schema, not a shared table with row filters, and CaseRead never trains on your data.

What you give up: KeyCite or Shepard's (the Shield's treatment warning is an automated screen, not a citator), headnotes, and editorial libraries like Practical Law and Practical Guidance. CaseRead also hasn't completed a SOC 2 audit. For the wider field, see our best AI legal research tools guide or the comparison hub.

The verdict

Choose CoCounsel if you already pay for Westlaw, your team reads KeyCite without thinking, you want Practical Law inside the AI, or your work leans on contract review and deposition prep.

Choose Lexis+ with Protégé if you already pay for Lexis, Shepard's is your citator, you want to pick among general AI models from several labs, or you want a free trial before a sales call.

Choose CaseRead if you pay for neither, your hard questions are about your own matter files as much as the law, and you want a price you can read before you sign. Run your last brief, or opposing counsel's, through the free Hallucination Shield, then try research on the free plan.

More head-to-head comparisons: Paxton AI review, Clio Work review, and our Irys One review.

Frequently asked questions

Is Lexis+ AI the same as Lexis+ with Protégé?

Yes. LexisNexis renamed Lexis+ AI to Lexis+ with Protégé in February 2026 and calls it the flagship platform that replaces Lexis+ AI. Existing Lexis+ AI users have access to the new platform. Protégé is the AI assistant inside it; the platform also carries LexisNexis primary law, secondary sources, Practical Guidance and Shepard's. A search for Lexis+ AI today describes the same product under its former name.

Does CoCounsel require a Westlaw subscription?

For case-law research, yes. Thomson Reuters sells CoCounsel Essentials on its own, but it is a document-analysis and drafting tool without Westlaw research. AI research over case law, including Deep Research, comes in the Westlaw Advantage with CoCounsel Essentials plan and the full CoCounsel Legal plan. Transactional and document-review users can stay on Essentials; research users are buying Westlaw.

Is CoCounsel more accurate than Lexis+ AI?

We found no independent study testing the current versions against each other. Stanford's May 2024 study found Lexis+ AI more accurate than Westlaw AI-Assisted Research, but it did not test CoCounsel, and Lexis+ AI has since become Lexis+ with Protégé. CoCounsel scored well on document tasks in the February 2025 Vals report, which LexisNexis withdrew from. Test both on a question you have already researched.

How much do CoCounsel and Lexis+ with Protégé cost?

Neither vendor lists a price for its AI bundle as of September 2026. Westlaw Advantage alone starts at $256.75 a month for single-circuit coverage and $399.75 for all states and federal, for new customers at firms of up to 10 attorneys. A third-party configurator pull in June 2026 quoted a solo $639.20 a month with CoCounsel Essentials added. LexisNexis quotes Protégé through sales.

Which is better for a small firm, CoCounsel or Lexis+ AI?

The one that sits on the database you already use. If your firm is on Westlaw and reads KeyCite, CoCounsel adds AI without retraining anyone. If you are on Lexis and rely on Shepard's, Protégé does the same. If you pay for neither, compare against tools with published prices and no base subscription before signing a multi-year research contract.

Is there an alternative to CoCounsel and Lexis+ AI without a Westlaw or Lexis subscription?

Yes. CaseRead, our product, researches public law across all 53 US jurisdictions together with your own case files from Google Drive, OneDrive or its built-in vault, at published prices: a free plan, Solo at $149 a month and Team at $199 per seat. It has no editorial citator, so it does not replace KeyCite or Shepard's. Its Hallucination Shield checks any brief's citations for free.