Westlaw UK
Thomson Reuters' UK legal research service, with AI-Assisted Research on Westlaw Edge UK and Deep Research on Westlaw Advantage UK. No published price.
Overview
Westlaw UK is Thomson Reuters' legal research service for the UK: cases, legislation, annotated statutes and retained EU legislation for England, Wales, Scotland and Northern Ireland (Westlaw UK). Its AI features come in two higher tiers:
- Westlaw Edge UK adds AI-Assisted Research, which Thomson Reuters launched in the UK in April 2024 (Thomson Reuters UK).
- Westlaw Advantage UK adds agentic AI tools: Deep Research and a Litigation Document Analyser (Westlaw Advantage UK).
For solicitors in England and Wales
This is a UK product on UK content. The AI answers are grounded in Westlaw's own database rather than the open web, which makes them more reliable than a general assistant's, but not reliable enough to cite unread.
A Stanford study tested the US version of Westlaw AI-Assisted Research on US law in 2024. It found that about one-third of its answers contained a hallucination, the highest of the legal research tools tested (Magesh and others, 2024). That study says nothing directly about the UK product today, but it shows why every authority needs checking.
Pricing
Checked 29 September 2026. Thomson Reuters publishes no UK price for Westlaw UK or its AI tiers. The UK product page offers a free trial and a sales contact.
Security and data
Checked 29 September 2026 against Thomson Reuters' own pages.
- Certifications. Westlaw is within the scope of Thomson Reuters' ISO 42001 certificate for AI management (Trust Center).
- Where data is held. No public statement of where Westlaw UK data is hosted was found. Thomson Reuters keeps a Westlaw UK security summary behind a login; ask for it before a firm-wide rollout.
Using it safely
- Read every authority an AI answer cites, and check its status, before relying on it. Paragraph 3.2 of the SRA Code of Conduct for Solicitors requires a competent service, and paragraph 3.5 keeps a supervisor accountable for work done through others.
- For AI drafting and document review on top of Westlaw, see CoCounsel.