Claude Cowork for lawyers: using it without exposing professional secrecy
What Cowork does with the folders you connect, according to Anthropic's own documentation, what changes from one plan to another, and a way of working where it only ever sees a pseudonymised copy.
Claude Cowork is the first AI assistant many lawyers have used that works directly on their files rather than on what they paste into a chat. That is what makes it useful, and it is also what makes it a professional secrecy question. Here is what Cowork actually does with the folders you connect, according to Anthropic's own documentation, and a way of working that keeps client files out of it.
1. What Cowork does with your folders
Cowork is an agent: you give it a task, it plans the steps and carries them out, reading, writing and creating files in the folders you have connected through the Claude desktop app. Anthropic describes two kinds of session.
- Cloud sessions. The agent loop runs on Anthropic's infrastructure. According to its help page on using Cowork safely, Claude's work, "including any local files it opens through the desktop app, is processed on Anthropic's servers rather than staying on your computer". Sessions and files are saved to the user's Claude account.
- Local sessions. The agent loop runs on your machine and code runs in an isolated virtual machine (Cowork architecture overview). The Claude model itself is not installed on your computer: to reason about a file, it has to read its contents. The documentation does not say that content stays on the device, and you should assume it does not.
“Be cautious about granting access to sensitive information like financial documents, credentials, or personal records. Consider creating a dedicated working folder for Claude rather than granting broad access.”
Anthropic's own advice is therefore the same as a bar council's: do not connect the folder where your client files live.
2. Training and retention depend on the plan
Cowork is available on the Pro, Max, Team and Enterprise plans (Cowork architecture). What happens to your data is not the same for an individual account and an organisation account. Checked on Anthropic's pages on 2 October 2026:
| Plan | Used for training? | Retention |
|---|---|---|
| Pro, Max | Yes if the "Help improve Claude" setting is on (source). Turn it off in Settings > Privacy. | Up to 5 years, de-identified, if training is on; 30 days after deletion otherwise (source). |
| Team, Enterprise | No, unless the organisation joins a partner programme (source). | Per the organisation's policy; transcripts are available to admins through the Compliance API (source). |
A Team or Enterprise plan is a better contractual framework: no training, a data processing agreement, retention set by the firm. It does not change the underlying fact. The contents of the files Claude reads are processed by a provider that is not bound by your professional secrecy.
3. What the profession says
The CNB guide "Ethics and artificial intelligence" (2026) asks lawyers to "systematically pseudonymise or anonymise data before any use of a generative AI tool" (our translation). The Paris Bar's model AI charter (July 2026) lists "cowork" among permitted uses, provided its other rules are strictly respected, including the ban on submitting anything covered by secrecy to a tool that has not been validated. In other words: Cowork, yes; Cowork on the raw file, no. The details are in our article on the CNB's recommendations.
4. A way of working: Cowork on a protected mirror
The principle is simple: Cowork only ever sees a folder in which nothing identifies your client. Hexagone AI produces that folder on your own computer.
- Point Hexagone AI at the case folder. It maintains a protected mirror that follows every change: names, companies, addresses, amounts and references are replaced, and the same person keeps the same pseudonym in every document.
- Check the detections in the preview pane and correct anything before the copy is used.
- Connect only the protected mirror folder to Cowork. Never the original folder, never your whole documents directory.
- Let Cowork work: chronology, summary of the other side's exhibits, first draft of a letter. It reasons on pseudonyms.
- Re-identify the result locally. The mapping between pseudonyms and real names never left your machine, so Hexagone AI puts the real names back on your computer.
To compare Claude with ChatGPT, Mistral and Copilot plan by plan, see Using Claude, ChatGPT or Mistral on a client file. For the method applied to law firms, see our page for lawyers.
Want to see how this works on your own files?