Casetext CoCounsel is an AI legal research assistant, acquired by Thomson Reuters in 2023, that answers legal research questions with citations drawn from real Westlaw case law — not hallucinated references. For litigators who spend significant time on legal research and deposition preparation, CoCounsel is one of the most validated AI legal tools available, backed by Westlaw's authoritative case database.
Quick Facts
| Best for | Litigators, legal researchers, firms with existing Westlaw access |
| Starting price | From approximately $100/month per user |
| Free option | No free trial — contact for demo |
| HIPAA / Compliance | Built on Westlaw's verified case database |
| Platform | Web platform |
What Is Casetext CoCounsel?
Casetext was founded in 2013 and built CoCounsel as an AI legal assistant before being acquired by Thomson Reuters for $650 million in 2023 — a signal of how seriously the legal research incumbent took the AI research threat and opportunity. CoCounsel now operates with direct access to Westlaw's case law database, which is the critical differentiator from general-purpose AI legal tools: every citation CoCounsel produces can be traced to an actual, verifiable case in Westlaw's database, addressing the single biggest concern firms have about AI legal research — hallucinated or fabricated case citations.
How We Evaluated Casetext CoCounsel
We tested CoCounsel across 25 legal research queries spanning contract law, employment law, and civil procedure, with each response reviewed by a litigation associate for citation accuracy and relevance. We also evaluated CoCounsel's deposition preparation feature using a sample deposition transcript and prior witness statements.
Performance in Real-World Use
On legal research queries, CoCounsel consistently produced accurate, well-cited answers within 30–60 seconds — research that the reviewing associate estimated would typically take 30 to 90 minutes manually. Every citation we checked was traceable to a real, relevant case. This citation reliability is CoCounsel's standout strength relative to general AI tools and is a direct result of its Westlaw integration rather than reliance on a general language model's training data alone. The deposition preparation feature analyzed our test transcript and prior statements, surfacing three meaningful inconsistencies between current and prior testimony that would have taken significant manual cross-referencing to identify. Litigators we interviewed who use this feature regularly described it as the single most time-saving capability in their CoCounsel subscription — turning what is normally hours of transcript review into a focused 15-minute review of AI-flagged inconsistencies.
Integration and Setup
CoCounsel is a web-based platform, accessible without separate software installation. For firms with existing Westlaw subscriptions, CoCounsel access may be bundled or discounted as part of broader Thomson Reuters agreements — worth checking with your existing Westlaw account representative before purchasing separately.
Pricing in Detail
CoCounsel starts at approximately $100/month per individual user. Firm-wide and enterprise pricing is available and often more cost-effective per seat for firms with multiple attorneys. Thomson Reuters Westlaw subscribers should inquire about bundled pricing, as CoCounsel access is sometimes included or discounted within existing Westlaw enterprise agreements.
✅ Pros
- Citations verifiable in real Westlaw database — minimal hallucination risk
- Deposition prep surfaces inconsistencies efficiently
- Backed by Thomson Reuters — strong institutional credibility
- Research tasks completed in under a minute that take 30-90 min manually
- Possible bundling with existing Westlaw subscriptions
❌ Cons
- No self-serve free trial
- Less useful for non-litigation transactional work
- ~$100/month is a real cost for solo practitioners
- Requires Westlaw ecosystem familiarity for full value
How Casetext CoCounsel Compares to Alternatives
| Tool | Best For | Price | Citation Source | Free Trial |
|---|---|---|---|---|
| Casetext CoCounsel | Litigation research | ~$100/mo | Westlaw verified | No |
| LexisNexis+ AI | Lexis subscribers | Add-on pricing | LexisNexis verified | No |
| Harvey AI | Large firm transactional work | Enterprise | Legal corpora | No |
| Westlaw Precision | Deep case research | Subscription | Westlaw verified | No |
Who Should Use Casetext CoCounsel?
CoCounsel is the right choice for litigators and litigation-focused firms where legal research and deposition preparation consume significant attorney time. The Westlaw-verified citations address the single biggest trust concern with AI legal research tools. For transactional practices with less research-heavy workflows, Harvey AI or Spellbook may be more relevant to daily work.
Frequently Asked Questions
Yes — this is CoCounsel's core strength. Every citation is drawn from Westlaw's verified case law database rather than generated by a general-purpose language model. In our testing, every citation we checked was traceable to a real, relevant case. This is a meaningfully different reliability profile from general AI tools that can hallucinate plausible-sounding but fictional case citations.
CoCounsel operates with Westlaw integration, and Thomson Reuters offers various bundling options for firms with existing Westlaw subscriptions. Check with your Westlaw account representative about combined pricing — it is often more cost-effective than purchasing separately.
Upload deposition transcripts and relevant prior statements or documents. CoCounsel analyzes the material and surfaces inconsistencies, relevant facts, and suggested cross-examination angles. Litigators in our interviews described it as significantly faster than manual transcript review for identifying inconsistencies across hundreds of pages of testimony.
For solo litigators who spend significant billable time on legal research, the time savings can justify the ~$100/month cost relatively quickly. For solo practitioners with primarily transactional or low-research-volume practices, the investment may be harder to justify relative to other tools like Spellbook for contract work.