Harvey AI vs CoCounsel

Legal AI with no published price, or legal AI bolted to Westlaw?

Last revised 2026-09-17

Our pick

CoCounsel, if you already pay for Westlaw

CoCounsel is grounded in Westlaw and Practical Law, which is the entire reason litigators trust it over a general chatbot, and most firms buying it already have the underlying subscription. Harvey is the better-known name with genuinely enthusiastic users, no published pricing, no trial, and accuracy claims resting on benchmarks it designed itself. Verify every citation from either.

Read the CoCounsel (Thomson Reuters) review

Side by side

	Harvey AI Legal AI	CoCounsel (Thomson Reuters) Legal AI Our pick
Our score	3 cydersDrinkable	3 cydersDrinkable
Starting price	Custom	Custom
Free plan	No	No
What the paid plans are	Custom enterprise pricing — contact for quote. No public pricing.	Bundled with Westlaw subscription — contact for pricing
Best for	Law FirmsIn-House Legal TeamsCorporate Legal Departments	Law FirmsLitigation TeamsLegal Researchers
Pros	✓Custom AI models trained on your firm's data ✓Advanced legal research across case law and regulations ✓Contract review with risk spotting and redlining ✓Seamless integration with existing legal workflows	✓Powered by GPT-4 with deep legal knowledge ✓Integrates with Westlaw and Practical Law ✓Handles contract review, drafting, and legal research ✓Backed by Thomson Reuters — trusted by large firms
Cons	✗Enterprise-only pricing (not transparent) ✗No self-serve signup — requires demo ✗Primarily designed for large law firms, not solo practitioners	✗Requires Westlaw subscription (expensive) ✗Not available as standalone product ✗Pricing not publicly disclosed
Price checked	2026-09-16	2026-09-16
Visit	Harvey AI →	CoCounsel (Thomson Reuters) →

Neither price is on a website

Harvey publishes no pricing and offers no free trial. CoCounsel is bundled with a Westlaw subscription and quoted rather than listed. You are negotiating in both cases, which means the comparison that matters is what your firm can extract, not what a page says.

Budget for the Westlaw seat as part of CoCounsel's real cost. Firms that already have it are comparing an add-on against a new platform, and that usually settles the question before anything else does.

The grounding argument

CoCounsel's answers sit on Westlaw and Practical Law content. That is the reason litigators tolerate it: the research it does is against material the firm already relies on, with citations into a system people know how to check.

Harvey's grounding is its own, and its accuracy claims rest on benchmarks the vendor designed. Twenty-eight public reviews is a thin evidence base for a platform-level commitment, even when the firms using it are enthusiastic.

The hallucination number nobody should skip

Peer-reviewed research from Stanford found leading legal AI tools in this family hallucinate more than seventeen percent of the time, and described the providers' accuracy claims as overstated. Lawyers also report confident, wrong summaries of documents they supplied, which is the failure mode that gets people sanctioned.

That figure is about the category, not one product. Treat every citation from either tool as unverified until you open it. Firms have been sanctioned for filing AI-invented cases, and no vendor's marketing will be at the hearing with you.

Thomson Reuters keeps moving the packaging

CoCounsel was repackaged as CoCounsel Legal in August 2025, bundling research, document search and agentic workflows with Westlaw Advantage. Older reviews describe the standalone Casetext-era product, which no longer exists in that form. If you are reading comparisons written before that date, they are describing a different thing.

How we would buy it

•Already on Westlaw, want AI research and drafting: CoCounsel, negotiated into the existing contract.
•Large firm with the leverage to run a proper pilot and negotiate terms: Harvey is worth the conversation.
•Small practice without an existing research subscription: neither. The total cost is higher than the tool suggests and the verification burden does not shrink.
•Anyone, whatever they buy: a citation-checking step in the workflow, owned by a human, every time.

Harvey AI

3.0Drinkable

Harvey is the best-known name in legal AI and the firms using it rate it highly, with only 28 public reviews to go on. Everything else is opaque: no published pricing, no free trial, and accuracy claims resting on benchmarks the vendor designed. If you are big enough to negotiate and pilot it properly, it is worth the conversation.

Full Harvey AI review

CoCounsel (Thomson Reuters)

3.0Drinkable

Grounded in Westlaw and Practical Law, which is the entire reason litigators trust it over a general chatbot. Peer-reviewed research from Stanford found leading tools in this family hallucinate more than 17% of the time and called the providers' accuracy claims overstated, and lawyers report confident, wrong document summaries. Verify every citation, and expect the real cost to include a Westlaw seat.

Full CoCounsel (Thomson Reuters) review

Scores are our own editorial verdicts in cyders out of 5, not an average of other people's ratings. How we score. Prices come from each vendor's own pricing page on the date shown above, and vendors change plans often, so confirm before you buy.

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