GPT-5 vs Claude 4.6 for Legal Contract Drafting & Review

Legal AI in Practice

AI in legal isn't hypothetical anymore—law firms from solos to AmLaw 100 are using language models daily. But which model produces output that lawyers can actually use? We tested GPT-5 and Claude 4.6 on five core legal tasks: contract drafting, clause review, risk analysis, regulatory compliance checking, and legal research summarization.

Our evaluation panel included three practicing attorneys (corporate, IP, and employment law) who rated outputs on accuracy, completeness, appropriate caution, and practical usefulness.

Contract Drafting

For drafting standard commercial agreements (NDAs, MSAs, SaaS terms), both models produce competent first drafts. Claude 4.6 tends toward more conservative, protective language—defaulting to stronger indemnification clauses and broader liability limitations. GPT-5 produces more balanced drafts that split risk more evenly.

Our attorneys preferred Claude's conservative approach for representing a single party (you want your client's contract to be protective), while GPT-5's balanced approach works better for negotiated agreements where both sides need acceptable terms.

Clause Analysis and Risk Identification

This is where Claude 4.6 clearly excels. Given an existing contract, Claude identifies risky clauses with higher accuracy (89% vs GPT-5's 78% in our test). More importantly, Claude provides specific explanations of why each clause is risky and suggests concrete alternative language.

GPT-5 occasionally misses subtle risks—for example, a limitation of liability clause that appears standard but contains an unusually broad definition of 'consequential damages.' Claude caught 8 out of 8 such nuances; GPT-5 caught 6.

Regulatory Compliance

For checking contracts against specific regulations (GDPR, CCPA, SOX), GPT-5 demonstrates broader regulatory knowledge. It correctly identified compliance gaps for regulations across more jurisdictions. Claude 4.6 is deeper on US and EU regulations but weaker on APAC and emerging market regulatory frameworks.

Both models appropriately caveat their analysis—neither claims to replace legal counsel. However, Claude is more consistent about flagging when it's uncertain, while GPT-5 occasionally presents uncertain analysis with inappropriate confidence.

Practical Recommendations

For law firms: Claude 4.6 is the safer choice. Its conservative defaults, superior risk identification, and consistent uncertainty flagging align with legal best practices. The longer context window (200K tokens) also handles large contracts and due diligence document sets better.

For in-house legal teams: GPT-5's broader regulatory knowledge and more balanced drafting style may be preferable when you're drafting agreements rather than reviewing them.

Critical caveat: neither model should be used for final legal work without attorney review. These are first-draft and analysis tools, not replacements for legal judgment.

Getting Started

Access both GPT-5 and Claude 4.6 through Vincony.com and test them on your actual legal documents. Compare outputs side-by-side with your firm's templates and standards. Start with 100 free credits—enough to evaluate both models on multiple contract types without commitment.