AI for law firms, without breaching client confidentiality
Drafting submissions, summarising a 40-document case file, comparing contracts: AI does it in minutes. Hidden Tokens lets your lawyers do it without your clients' names, company numbers or case references ever leaving the firm.
- Every party, witness, company and case reference in the file is replaced by a consistent code on the lawyer's computer, before Claude or ChatGPT reads anything.
- Courts, statutes, codes and legal sources stay readable, so the AI can still reason about the law.
- The draft comes back in Word with the real names restored, on the same computer. The key never leaves the firm.
- Professional-conduct guidance such as the ABA's Formal Opinion 512 asks lawyers to protect client information when using generative AI; keeping identities out of the AI is the simplest way to show you did.
The problem with case files and AI
A case file is the worst possible thing to paste into a chatbot: it is full of names, addresses, company numbers, bank details and, often, health or family information. Once uploaded, it sits on the AI provider's servers under that provider's terms. For a profession built on confidentiality, "the provider promised not to train on it" is a thin answer to give a client.
Bar regulators have noticed. The American Bar Association's Formal Opinion 512 (July 2024) reminds lawyers that the duty of confidentiality applies when they use generative AI, and that they must understand how a tool handles client information before entering it. Other bars, including the French national bar council, have issued similar guidance.
How Hidden Tokens fits a law firm
- Drop the case folder into a folder Hidden Tokens watches. Every Word, PDF, Excel and text document is coded within seconds into a
Hidden-Tokens/subfolder next to the originals. - Work in Claude or ChatGPT on the coded copies: "Draft submissions for
NOM-001againstSOC-002", "Summarise the exhibits", "List the inconsistencies between the two witness statements". - Get the draft back in clear. Hidden Tokens puts the real names and references back into the Word file the AI produced, formatting intact, on your computer.
What the legal pack codes, and what it keeps readable
| Coded | Kept readable |
|---|---|
| Parties, witnesses, counsel, judges' names | Courts and institutions |
| Companies, addresses, emails, phone numbers | Codes, statutes and legal sources |
| SIRET and SIREN numbers (checksum verified) | Procedural vocabulary |
| Docket (RG), prosecutor and appeal numbers | Dates and deadlines |
| IBANs, card numbers, ID and passport numbers | Amounts, unless you choose to protect them |
Indirect identifiers ("the managing partner of a Lyon biotech, born in 1971") are flagged in the plan so you can generalise them before anything is sent.
For the whole firm
- One registry for the firm: the same client gets the same code on every lawyer's computer, in every case, kept encrypted on your own file share.
- A policy signed by your administrator: rules, packs and forbidden items pushed to every machine.
- The browser too: the Hidden Tokens extension codes what lawyers type into ChatGPT, claude.ai, Gemini or Copilot before it is sent.
- Proof: a local log of everything the AI received, a coverage report per workstation for the managing partner, and a signed seal for the client.
Hidden Tokens supports your compliance; it does not replace your professional judgement or certify compliance. See how to use ChatGPT or Claude with client data for the wider picture.
Frequently asked questions
Does Hidden Tokens work with legal documents in English?
Yes: names, companies, addresses, emails, phone numbers, IBANs and card numbers are detected in any language. The legal pack itself was built for French procedure (SIRET and SIREN numbers, RG docket numbers, prosecutor and appeal references); identifiers specific to other jurisdictions can be added as custom rules or a custom pack. Our benchmark also shows the engine still codes too many ordinary English words; we are fixing it.
Will the AI still understand the case if names are coded?
Yes. Each person and company keeps the same code across the whole case file, so the AI can follow who did what. Only the identity is hidden; the facts, dates and legal reasoning stay intact.
Can my client verify that their file was protected?
Yes. Hidden Tokens can issue a signed seal for a case file, which the client can verify themselves on a public verification page without uploading anything.