Lexis AI vs CoCounsel for Small Law Firms: Lexis+ AI and Westlaw CoCounsel Price, Research and Document Review

Short answer. For a small law firm, the choice between Lexis AI and CoCounsel is mostly a choice between research libraries. Lexis+ with Protégé is the better buy for a firm already on Lexis, especially litigators who lean on Shepard's. CoCounsel is the better buy for a firm already on Westlaw or Practical Law. Neither publishes a seat price: buyers report roughly $128 to $494 per user per month for Lexis+ with Protégé and $104 to $784 for CoCounsel, with about $639 cited for a solo Westlaw Advantage seat with CoCounsel Essentials. If your real AI need is reviewing contracts and documents rather than researching case law, you may not need either.

Below is the side-by-side a small firm actually needs: what each one costs, what it is good at, what the security paperwork says, and a plain rule for choosing.

Lexis AI vs CoCounsel at a glance

Every price above is either published by the vendor or labeled as reported by third parties. The Stanford figures tested the 2024 versions of both products, and both vendors have shipped new generations since, so treat them as a reason to verify output, not as a current ranking.

Which is cheaper, Lexis+ AI or CoCounsel?

On reported figures, Lexis+ AI is usually cheaper for a small firm. Reported Lexis+ with Protégé seats start around $128 per user per month and commonly land between $250 and $500 all in, while the most cited solo CoCounsel configuration on Westlaw Advantage is about $639. Both are quoted, so your content package and term decide the real number.

Run it for a three-attorney firm on one-year terms. At $250 per Lexis seat, the firm pays $750 a month, or $9,000 a year. At $500, it pays $18,000. Three Westlaw Advantage seats with CoCounsel Essentials at about $639 come to roughly $1,917 a month, or $23,004 a year. Multi-year terms bring both down, by around a quarter on the Lexis store plans, but lock the firm in for the life of the contract.

The per-use route looks cheap and rarely is. Lexis is the only one of the two that publishes AI charges per use, and at $99 per Generative AI Ask, a lawyer who asks five questions a month has already spent $495. Our Lexis AI pricing breakdown tables every published charge and reported seat figure, and the CoCounsel pricing page does the same for the four Thomson Reuters plans.

Is Lexis+ AI better than CoCounsel?

For case law research, Lexis+ AI tested better: the 2024 Stanford RegLab and HAI study found it accurate on 65% of queries against 42% for Westlaw's AI-Assisted Research. CoCounsel is broader on document work and drafting, and it is the stronger pick if your firm relies on Practical Law templates. Neither result makes checking citations optional.

In day-to-day use, the library you already trust matters more than the model. A litigator who has built a decade of Lexis searches and reads Shepard's signals by habit will get more from Protégé in the first week. A transactional lawyer who starts every deal from a Practical Law standard document will get more from CoCounsel. Switching libraries to chase an AI feature is an expensive way to learn that.

What is the difference between Protégé and CoCounsel?

Protégé is the LexisNexis AI assistant inside Lexis+ with Protégé, which replaced Lexis+ AI in February 2026 and is grounded in LexisNexis content. CoCounsel is the Thomson Reuters AI assistant, grounded in Westlaw and Practical Law and sold either as CoCounsel Essentials attached to those subscriptions or as the fuller CoCounsel Legal tier.

The product roadmaps have converged. Both now advertise multi-step agentic workflows, both keep a document store for AI work, and both run on frontier models from outside vendors. The practical differences for a small firm are the research content, the citator, how each is bought, and which security documents you can see before signing.

Security and confidentiality for a small firm

Both vendors say your data does not train their models. LexisNexis states that it never uses customer data to train AI models and that its model partners are bound not to train on it; since May 2026 it has offered Protégé BYOK, which lets a firm hold its own encryption keys in AWS KMS, Azure Key Vault, Google Cloud KMS or HashiCorp Vault. Thomson Reuters lists ISO 27001 and ISO 42001, publishes its DPAs, describes zero-retention calls to its model providers, and supports SAML 2.0 SSO, while keeping SOC reports behind its trust portal.

For most small firms either set of controls is more than enough to satisfy ABA Formal Opinion 512, provided someone actually reads the terms. If a client's outside counsel guidelines ask for specific documents, request them from both vendors before the demo, not after. We went through the Thomson Reuters controls line by line in our Westlaw AI security and confidentiality review.

Which one should a small law firm choose?

• Already on Lexis, litigation-heavy: Lexis+ with Protégé. You keep your research habits, Shepard's runs inside the answer, and the reported seat cost is lower.
• Already on Westlaw or Practical Law: CoCounsel. The AI sits on content you already license, and Practical Law users get the most out of its drafting side.
• On neither, and research is occasional: do not sign a multi-year research contract to get an AI feature. Price the research you actually do first; for occasional questions, a plain-English case law search tool can cover the gap for far less.
• Your AI need is reading documents, not researching law: neither is built around that job. See the section below.

Questions to ask on both sales calls

1. What is the per-seat price at our headcount on a one-year term, with and without the AI layer?
2. Which jurisdictions and libraries are in the quote, and what does adding one more state cost?
3. Are AI uses unlimited on this plan, or will anything bill per use outside it?
4. What is the renewal increase cap, and when is the cancellation notice window?
5. Which security documents can we see before signing: SOC report, DPA, subprocessor list?
6. Can we run the AI on one of our own matters before we commit?

Question three matters more with Lexis, because its per-use charges are published and apply to anything outside a flat-rate plan. Question five matters more with Thomson Reuters, because its SOC reports sit behind a gated portal.

When you need document review, not research

A lot of small firms shopping for Lexis AI or CoCounsel are really trying to solve a different problem: a stack of contracts, a commercial lease, a production of exhibits that someone has to read closely this week. Both platforms can do that, but you would be buying a research subscription to get there, and on Lexis per-use terms a single uploaded document summary is $250.

LegalSoul does that one job. Upload a contract, brief, lease or exhibit, and in under a minute you get a structured review with issues, risky clauses, missing terms and page cites. It is not a research tool and does not replace Shepard's or KeyCite. It also has no SOC 2 report and no SAML SSO today, so a firm whose clients require those should keep them on the checklist. What it does have is a published price: $99 a month for 100 reviews, $299 for 500, and no seat minimum or sales call. The first review runs without an account, so you can check its read of a document you know before either vendor has sent a quote. Solo attorneys comparing a wider field can see fourteen tools priced in our guide to the best AI for solo practitioners.