Westlaw

Westlaw is a legal research platform from Thomson Reuters that helps attorneys find case law, statutes, regulations, and secondary sources using AI-powered search backed by 150 years of editorial expertise, with subscription pricing typically negotiated per-seat for law firms, corporate legal departments, government agencies, and law schools. It is designed for practicing attorneys, paralegals, judges, and legal researchers who need verified, citable answers rather than unsourced AI-generated text.

The platform is anchored by KeyCite citation analysis, the West Key Number System, and a corpus of editorially enhanced primary and secondary law that powers headnotes, annotations, and topic indexes built by Thomson Reuters' attorney-editor staff. Westlaw is offered in multiple tiers — including Westlaw Edge and the newer Westlaw Advantage tier with agentic AI — and integrates tightly with CoCounsel Legal, Thomson Reuters' generative AI assistant, as well as Practical Law's 650+ attorney-editor-curated guides, templates, and checklists. Recent product updates emphasize AI-Assisted Research that delivers narrative answers grounded in Westlaw content, complete with citations and KeyCite signals so practitioners can verify every source.

Based on our analysis of 870+ AI tools, Westlaw is one of the most established players in legal research and the primary head-to-head competitor to LexisNexis. Compared to newer entrants like Harvey, Casetext (now part of Thomson Reuters via CoCounsel), and Paxton AI, Westlaw differentiates on the depth of its proprietary editorial layer and the sheer breadth of its primary-law database, while being notably more expensive and less flexible than open-web alternatives like Fastcase or Free Law Project. Customer evidence published by Thomson Reuters includes Justly Prudent reporting 5x ROI and 100% increased litigation capacity using CoCounsel and Westlaw AI, and Brinks using CoCounsel to cut outside counsel spend.