# Claude for Lawyers — Use Claude for Legal Work Safely with Relex

> How to use Claude for legal work without exposing client data. Connect Claude to Relex over MCP: Claude reasons and drafts on real matters while client identities stay encrypted in your browser and the AI only sees labels like [Party 1].

# 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.

## The moment client names enter a chat window

Every lawyer who has used an assistant knows the moment. The matter is real, the deadline is close, and the fastest way to get help is to paste the letter in, names and all. That single paste is the whole risk, and being careful next time does not undo it.

Anthropic itself recommends being thoughtful about sharing highly sensitive personal details with Claude. Relex takes that seriously enough to make it structural. Identities are sealed in your browser before any request is made, and the server holds no key to undo it, so there is no path by which a client's name reaches the model. If a connected agent asks the server for plaintext personal data, the request is refused and the agent is handed a deep link so you complete that step yourself.

The answer to "how do I use Claude on a real client matter" is not to be careful. It is to make carelessness impossible. See [the best legal plugin for Claude](/guides/best-legal-plugin-for-claude) and [how the encryption works](/security).

## 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: client identities (names, IDs, contacts) are encrypted on your device under a password only you hold, documents are de-identified in your browser, 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-claude` then `/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 (Pro / Max):** Customize → Connectors → Add custom connector, name it Relex, URL `https://relex.you/api/mcp` (leave the OAuth fields blank). Then click **Connect** and sign in.
- **Claude Team / Enterprise:** members can’t add connectors — an owner or admin adds the custom connector once in the organisation’s settings (Connectors), using the same URL. Each member then opens Customize → Connectors, finds Relex under available connectors, and clicks **Connect** to sign in.
- **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.

[MCP Quickstart](/docs/mcp/quickstart) [How data protection works](/security)

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_[View this page on relex.you](https://relex.you/claude-for-lawyers)_