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Casetext

CoCounsel (Casetext)

Legal AI from Thomson Reuters, strongest on US caselaw and legal research.

Finance & Legal AI Active #Legal#LegalResearch#Enterprise#AIforLaw

In short

AI legal research and document analysis from Casetext, now part of Thomson Reuters. Deep integration with Westlaw and a long track record in US legal research distinguish it from newer entrants.

What it is best at

  1. US caselaw research and citation checking
  2. Deposition preparation and key issue extraction from document productions
  3. Contract analysis and quick-turn research memos

Built for: Compliance/Audit Professionals · Enterprise Operations

Technical foundation

Base model
Built on GPT-4 with legal-domain fine-tuning and Westlaw retrieval.
Context and file handling
Legal documents, contracts, deposition transcripts, and production sets.
Latency
Fast for research tasks.
Output quality and limits
Strongest on US common law. The Thomson Reuters integration gives it a sourcing depth other tools lack. Still requires lawyer review.

Pricing and access tiers

TierModelKey inclusionsLimits
Firm subscriptionPer-seat monthly or annualResearch, document analysis, Westlaw integrationContract-based

Pricing, version numbers, context-window sizes, and compliance certifications change frequently. Where stated they are accurate as of the as_of date and should be confirmed with the vendor before any procurement or compliance decision. Where they could not be stated confidently they are omitted rather than guessed.

Security, privacy and governance

Training data opt-out
Thomson Reuters / Casetext terms govern customer data use. Verify under the current agreement.

The governance question this raises

Same professional responsibility framing as Harvey: the tool accelerates, the lawyer is still accountable. The Westlaw integration is specifically valuable for the sourcing chain, because a hallucinated citation is immediately checkable rather than requiring a separate lookup. Attorney-client privilege analysis for the data path applies as with any legal AI.

No compliance certifications are listed here. Certification status is vendor-specific and time-specific, so it is stated only where verified rather than assumed. Check the vendor’s trust centre and confirm it covers the specific tier you are buying.

Integrations and ecosystem

  • Westlaw (Thomson Reuters)
  • Standard legal document management systems

API and SDKs: Via Thomson Reuters platform.

The verdict

Strengths

  • Deep Westlaw integration for US law
  • Established trust record in law firms
  • Thomson Reuters data governance backing

Drawbacks

  • US caselaw focus limits international utility
  • Lawyer review still mandatory
  • Less generalist than Harvey for corporate transactional work

Consider instead: Harvey AI, Microsoft Copilot, ChatGPT

Frequently asked questions

What is CoCounsel (Casetext) used for?

AI legal research and document analysis from Casetext, now part of Thomson Reuters. Deep integration with Westlaw and a long track record in US legal research distinguish it from newer entrants.

What model does CoCounsel (Casetext) run on?

Built on GPT-4 with legal-domain fine-tuning and Westlaw retrieval.

Does CoCounsel (Casetext) train on your data?

Thomson Reuters / Casetext terms govern customer data use. Verify under the current agreement.

What are the alternatives to CoCounsel (Casetext)?

The closest comparable tools are Harvey AI, Microsoft Copilot, ChatGPT. Which fits depends on where the work already lives and what the organization's data terms require.

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