Claude for lawyers: how to use Claude for legal work safely
Claude — including Anthropic's Claude for Legal — is excellent at legal reasoning and drafting.
Relex is the companion that makes it safe and complete for real client work: it protects
confidential data, runs the matter end to end, lets your team and outside professionals
collaborate, and onboards your clients and their data. Claude does the reasoning; Relex keeps
client identities encrypted in your browser (the AI only ever sees labels like [Party 1]),
gives each matter a formal ontology, and keeps your know-how private. Relex is an independent
platform that works alongside Claude and Claude for Legal — it is not an Anthropic product.
What Relex adds to Claude (and Claude for Legal)
Confidential data, protected
Client identities are encrypted in your browser under a password only you hold. The AI — Claude or Claude for Legal — works on labels like [Party 1] and never sees plaintext personal data.
End-to-end execution
Run the whole matter in one workspace: intake, the formal case ontology, drafting and redline against your playbooks, the clause-enforceability gate, and delivery.
Collaboration
Bring your team and invite outside professionals into a case with the right scope. Partners contribute know-how to the case they are invited to — never your full library, never decryption.
Client onboarding
The agent onboards your clients and their documents — extracting and encrypting parties and indexing know-how — so the matter is structured fast, without exposing anyone’s data.
Is it safe to put client data into Claude?
Not directly — pasting client names, IDs, or documents into any general chat exposes them. Relex fixes this with a zero-knowledge, in-browser design: personal data is encrypted on your device under a password only you hold, and the server never returns plaintext PII. When Claude works through Relex it sees de-identified labels and anonymized counts only. If Claude tries to touch real personal data, the server refuses and hands you a deep link to do that step securely in Relex yourself.
How do I connect Claude to Relex?
You connect over OAuth — there is no API key to paste.
- Claude Code: run
/plugin marketplace add relexyou/relex-claudethen/plugin install relex-legal@relex, reload, and say “Set up my practice workflow with Relex.” Your browser opens to sign in and approve. - Claude desktop / claude.ai / mobile: Customize → Connectors → Add custom
connector, URL
https://relex.you/api/mcp. Sign-in is automatic the first time. - CI / headless: create a key in Settings → API Keys and pass it as a Bearer header.
What can Claude do once connected?
Claude works through two tools — search to discover endpoints and execute to call them — about 1,000 tokens of context, with plain arguments and no
code to write. It can read your cases, reason about the matter, draft documents, and record its
work back to the case. It cannot add know-how, create parties, upload documents, or move
plaintext PII — those happen in Relex, in your browser, and Claude deep-links you there.
How does Relex keep Claude rigorous, not just fluent?
Two ways. First, the formal case ontology grounds Claude in the matter's real parties, issues, claims, and statutes instead of free-associating. Second, the clause-enforceability gate: when you review or draft a clause, Claude and Relex reach an explicit, law-grounded agreement on whether it holds — and when they disagree, the clause is flagged and a human professional is the tiebreaker. A clause left flagged unenforceable blocks the draft from going out for signature until a person resolves it.
Connect Claude to Relex
Bring your own Claude. Keep your clients' identities encrypted in your browser.