CoCounsel vs Harvey vs ChatGPT — Which AI Should Lawyers Use?
Every legal conference I’ve attended in the past year has had at least one panel debating CoCounsel vs. Harvey vs. “just use ChatGPT.” The audience is always split into three camps, each convinced their choice is obviously correct.
Having researched all three extensively, I think they’re all right — for different situations. These tools serve different types of lawyers with different budgets and different needs. Here’s how they actually compare.
Quick Comparison
| Feature | CoCounsel | Harvey | ChatGPT Plus |
|---|---|---|---|
| Price | $100-200+/mo | Enterprise only | $20/mo |
| Verified citations | ✅ Westlaw | ✅ Yes | ❌ Fabricates |
| Document analysis | ✅ Excellent | ✅ Excellent | ⚠️ Basic |
| Firm customization | ⚠️ Limited | ✅ Deep | ❌ None |
| Data privacy | ✅ Enterprise | ✅ Enterprise | ⚠️ Consumer |
| Availability | Wide | Limited | Universal |
| Best for | Research-heavy | Large firms | Everyone else |
CoCounsel: The Research Powerhouse
What it is: Thomson Reuters’ AI assistant, built on GPT-4 and integrated with Westlaw.
Strengths:
- Citations come from Westlaw’s verified database — the hallucination problem is largely solved
- Seamless Westlaw integration — click through from AI answer to full case text
- Document review and analysis features are mature
- Available to any firm with a Westlaw subscription
Weaknesses:
- Expensive on top of already-expensive Westlaw
- Limited to the Westlaw ecosystem
- Less flexible than general AI tools for non-research tasks
Best for: Litigation firms, research-heavy practices, anyone who needs reliable citations.
Harvey: The Enterprise Platform
What it is: A legal AI startup backed by Sequoia, building a comprehensive AI platform for large law firms.
Strengths:
- Deep firm customization — learns your templates, style, and preferences
- Trained specifically on legal data for better legal reasoning
- Enterprise-grade security and data isolation
- Broad capabilities: research, drafting, analysis, compliance
Weaknesses:
- Limited availability — not every firm can get access
- Enterprise pricing puts it out of reach for small firms
- Still relatively new — long-term track record unproven
- Vendor lock-in risk
Best for: Am Law 200 firms, large legal departments, firms willing to invest in a comprehensive AI platform.
ChatGPT Plus: The Accessible Option
What it is: OpenAI’s general-purpose AI assistant with GPT-4.
Strengths:
- $20/month — accessible to every lawyer
- Extremely flexible — handles any task you can describe
- Constantly improving with new features
- Huge ecosystem of guides, prompts, and community knowledge
Weaknesses:
- Fabricates case citations — never trust a citation from ChatGPT
- Consumer-grade data privacy (upgrade to Enterprise for $60/mo for better privacy)
- No legal-specific training
- Requires prompt engineering skill for best results
Best for: Solo practitioners, small firms, any lawyer who wants AI benefits on a budget.
Recommendations by Firm Size
Solo Practitioner
Use: ChatGPT Plus ($20/mo) + careful verification Why: The cost of CoCounsel or Harvey doesn’t make sense for one attorney. ChatGPT handles 80% of use cases. Just never trust its citations.
Small Firm (2-10 attorneys)
Use: ChatGPT Plus for drafting + CoCounsel for research (if on Westlaw) Why: Split the tools by function. Use the cheap tool for drafting and the expensive tool only for research where citation accuracy matters.
Mid-Size Firm (11-50 attorneys)
Use: CoCounsel for the firm + ChatGPT Enterprise for individual use Why: CoCounsel covers research needs. ChatGPT Enterprise provides a secure general-purpose AI for everything else.
Large Firm (50+ attorneys)
Use: Evaluate Harvey for firm-wide deployment Why: The customization and integration capabilities justify the investment at scale. The per-user cost decreases with volume.
The Hybrid Approach
Most firms will end up using multiple AI tools:
- CoCounsel for legal research (verified citations)
- ChatGPT/Claude for drafting and general tasks (speed and flexibility)
- Spellbook or similar for contract-specific work (specialized features)
There’s no single AI tool that does everything well. The smart approach is matching the right tool to the right task.
The Bottom Line
- Need reliable citations? → CoCounsel
- Need firm-wide AI transformation? → Harvey
- Need affordable, flexible AI? → ChatGPT Plus
- Need all three? → You probably do, and that’s okay