ChatGPT 5.0 vs Claude Sonnet 4.5 vs Gemini 2.5 Pro: Which AI Should Attorneys Actually Use?

Lawyer-centric comparison with citations, context windows, privacy controls, and ABA compliance guidance.

By Michael Clendening, Founder of EverIntent | October 27, 2025 | 10 min read

Executive Summary

We tested ChatGPT 5.0 Pro, Claude Sonnet 4.5, and Gemini 2.5 Pro on real legal tasks: contract review, client emails, legal research, and complex analysis. Each model has distinct strengths—Claude excels at reasoning-heavy contract review, ChatGPT leads in natural client communication, and Gemini handles massive documents fastest. The right choice depends on your task and privacy requirements. This guide shows you exactly which model to use when, with ABA compliance considerations and enterprise privacy guidance.

The Quick Take (For Busy Attorneys)

ChatGPT 5.0 Pro

If you're drafting or analyzing across varied fact patterns with solid web citations: ChatGPT 5.0 Pro now includes ChatGPT Search with inline citations and connectors to Gmail/Calendar—useful for quick fact checks and pulling matter context, with a 400K context length in the flagship offering.

Claude Sonnet 4.5

If you're working with long records and want grounded outputs from your own docs: Claude Sonnet 4.5 supports citation-grade grounding ("Citations" API) and offers 1M token context availability—excellent for long briefs, discovery summaries, and IRAC-style memos when you provide the sources.

Gemini 2.5 Pro

If you want built-in "double-check" verification and tight Google ecosystem integration: Gemini 2.5 Pro ships with "Double-check" (Search-grounded verification) and 1M-token context (2M coming), plus strong Workspace and Vertex AI governance for firms already on Google.

What Matters to Lawyers

"Should I use ChatGPT, Claude, or Gemini?" This question comes up in every legal tech conversation. The answer depends on five critical factors attorneys actually care about: verifiable answers with citations, long-document handling, privacy and training policies, ecosystem fit with your practice tools, and ABA compliance considerations.