Artificial Intelligence is revolutionizing many professional industries, and the field of law is no exception. In particular, AI tools dedicated to legal writing are becoming popular among law firms, legal tech companies, and independent practitioners. These tools are designed to accelerate and enhance tasks such as contract drafting, legal briefs, and client correspondence. But with a growing number of platforms available, choosing the right one can be a daunting task.
TLDR: Looking for the best AI tool for legal writing? This article compares top platforms that cater to tasks such as contract drafting, legal briefing, and client correspondence. We found that tools like LawGeex, Casetext CoCounsel, and Spellbook each offer unique strengths depending on your specific legal writing needs. Read on for a detailed breakdown that will help you choose the ideal solution for your practice.
Why AI is Transforming Legal Writing
Legal professionals traditionally spend a considerable amount of time writing contracts, preparing court briefs, and drafting correspondence for clients. This work is time-intensive, can be repetitive, and requires a high level of accuracy. AI tools are game changers in this landscape, significantly reducing time while maintaining (and sometimes even improving) the quality of legal documents.
These tools use natural language processing, machine learning algorithms, and access to extensive legal databases to draft and refine documents based on user input. Let’s dive into a comparison of the best AI tools for different types of legal writing.
Best AI Tools by Legal Document Type
1. Contract Drafting: LawGeex and Spellbook
LawGeex is one of the pioneering AI contract review platforms. It allows legal teams to automate the review and redlining of contracts based on a company’s internal legal policies. What makes LawGeex particularly effective is its ability to spot non-standard clauses and suggest modifications, saving hours of manual review.
Spellbook, formerly called Rally, integrates directly into Microsoft Word, enabling lawyers to draft smarter contracts in familiar environments. It’s powered by GPT-4 and tailored specifically for legal use cases, meaning it understands clause structures and can suggest entire sections based on context.
- Best for: Quick contract reviews and clause recommendations
- Strength: Seamless real-time suggestions during drafting
- Weakness: May need customization for niche legal frameworks
2. Legal Briefs: Casetext CoCounsel and Harvey AI
Writing legal briefs often involves legal research, citations, and rigorous analysis. AI tools for this category go beyond templates — they offer in-depth, evidence-backed assistance.
Casetext CoCounsel, developed by Casetext in collaboration with OpenAI, claims to be the first AI legal assistant. It can conduct legal research, summarize case law, and even draft arguments based on a user’s outline. The standout feature is that it cites actual laws and cases, making it a robust research companion.
Harvey AI is another next-generation platform tailored for elite law firms. Backed by OpenAI and Sequoia, Harvey has been trained on vast troves of legal data and can generate highly accurate briefs with proper legal references. Although still in closed beta in many regions, it has already shown superior pattern recognition and legal reasoning.
- Best for: Complex litigation briefs and nuanced arguments
- Strength: High-level legal research capabilities
- Weakness: Higher cost and limited availability as of now
3. Professional Correspondence: ChatGPT Legal Custom Versions
Client emails, short memos, and formal letters may not be as research-heavy as contracts or briefs, but they still require precision, tone, and clarity. This is where customizable AI tools like ChatGPT’s legal-tailored versions shine.
With tools like OpenAI’s ChatGPT (especially the GPT-4 version), users can create custom instructions for legal tone, terminology, and formatting. These modifications ensure the language remains formal, strategic, and compliant with firm policies. Lawyers can quickly draft responsive emails, compliance reminders, or consultation summaries without repetitive rewriting.
- Best for: Simplifying daily communications
- Strength: High flexibility and custom tone control
- Weakness: Requires good prompts and quality checks
Key Feature Comparison
| Tool | Best Use Case | Strength | Weakness |
|---|---|---|---|
| LawGeex | Contract Reviews | Policy-aligned redlining | Initial setup time for internal policy integration |
| Spellbook | Drafting smart contracts | Word integration, real-time suggestions | General legal knowledge may need fine-tuning |
| Casetext CoCounsel | Brief Writing, Legal Research | Case citation and logic construction | Needs supervision for complex multi-jurisdictional issues |
| Harvey AI | Complex Legal Briefs | Elite-level analysis and reasoning | Still in limited beta; expensive pricing |
| ChatGPT Legal Versions | Emails and Letters | Highly customizable tone | Accuracy depends on user input quality |
Security and Compliance Considerations
One of the most critical concerns with any AI application in law is the issue of confidentiality. Reputable AI legal tools offer encrypted data storage, role-based access controls, and options for on-premise deployment.
Firms dealing with sensitive information should specifically ask:
- Does the platform comply with GDPR and other regional privacy laws?
- Is your data used to train the AI model further without your consent?
- Are there protections against hallucination (incorrect information generation)?
For example, Harvey AI and CoCounsel take great precautions to operate in a secure, compliant environment for Fortune 500 law firms, while applications like ChatGPT’s legal variants are improving their enterprise-grade controls.
Are Humans Still Needed?
Absolutely. While AI significantly aids productivity, no tool completely removes the necessity for human legal judgment. Contracts still require custom negotiation points, and briefs must align with a client’s litigation strategy. Likewise, correspondence demands a human understanding of interpersonal dynamics and legal risk.
The real value lies in augmenting humans — freeing legal professionals from mundane tasks to focus on strategy, advocacy, and judgment-driven work.
The Bottom Line
Choosing the best AI tool for legal writing depends heavily on your specific needs:
- Use LawGeex or Spellbook if your priority is contract efficiency and consistency.
- Opt for Casetext CoCounsel or Harvey AI for deep litigation research and persuasive writing.
- Go with ChatGPT or similar tools for client-facing communication at scale.
With rapid innovation, we can expect these tools to become even more sophisticated in coming years, making adoption not just a competitive edge but a necessity for modern legal practice.
Experiment with small pilot runs and evaluate results based on accuracy, time saved, and client satisfaction. AI won’t replace lawyers — but lawyers who use AI will surely outpace those who don’t.
