Westlaw

What It Does

Westlaw is the legal research platform from Thomson Reuters — one of the two products (alongside LexisNexis) that most US lawyers learn in law school and use throughout their careers. It provides searchable case law, statutes, regulations, secondary sources, and practice materials, plus citation tools that tell you whether a case is still good law.

The product’s signature features are its editorial layer and its citator. The West Key Number System, a topic-classification scheme that predates the database itself, organises case law by legal issue. KeyCite, introduced in 1997, flags whether a cited authority has been overturned, criticised, or otherwise affected by later decisions — a core safety check in legal research.

More recent versions fold in AI: Westlaw Edge (2018) added AI-assisted search, and Thomson Reuters has since integrated its CoCounsel generative-AI assistant into the research workflow.

Who It’s For

Litigators and researchers at firms of every size — Westlaw is a default research tool across BigLaw, mid-size, and many small firms. The depth of editorial annotations and the KeyCite citator are the main reasons firms pay for it over cheaper alternatives.

Law students and academics — Westlaw is standard in US legal education, which feeds long-term familiarity and lock-in once those students enter practice.

In-house and government legal teams — Used for research, though some departments weigh the subscription cost against lower-priced research tools.

What We Found

Westlaw was launched in 1975 by West Publishing as one of the first computerised legal research databases, building on West’s much older print reporter and Key Number business. Thomson Corporation acquired West in 1996; the combined company became Thomson Reuters in 2008. The product has gone through several generational rebrands — Westlaw.com (1998), WestlawNext (2010), Westlaw Edge (2018), and most recently Westlaw Advantage.

Pricing is not publicly published and varies widely by firm size, practice areas, and content packages — Westlaw and LexisNexis subscriptions are a significant recurring line item for most firms. As a Thomson Reuters product brand rather than a standalone company, Westlaw doesn’t have its own headquarters, headcount, or funding figures; those belong to the parent (see the Thomson Reuters entry).

What We Haven’t Verified

• Current pricing — not published; negotiated per firm
• Subscriber numbers and market-share figures vs LexisNexis
• AI search accuracy claims for Westlaw Edge / CoCounsel integration
• The boundaries between Westlaw and adjacent Thomson Reuters products under the “Advantage” rebrand