The rule in three colours:

The one-sentence test. When you're unsure, ask: would I be comfortable seeing this on a public website with my organisation's name on it? If yes, it's green. If you'd wince, it's at least yellow. If it could hurt a person, a partner or the business, it's red. When in doubt, go one colour up.

Three ways to work with red material anyway:

1. Anonymise first. Remove or replace names, customer names, sample IDs linked to people, prices and anything else that points to someone. Be careful: a rare disease plus a town plus an age can identify a person without a name. If you can't make it harmless, it's still red.
2. Ask about the form, not the content. Don't paste the contract; ask "What are the usual payment and liability clauses in a supply contract, and how do I find them quickly?" Don't paste the manuscript; ask "What questions should a half-page summary answer if my PI must decide whether to join a follow-up study?" You do the reading with a better plan.
3. Use an approved tool with a proper agreement, within what your organisation has cleared for it. Some red material may be cleared for an approved tool; some never is. A local model, an AI that runs on your own laptop (T11-L01 · Run an AI Model on Your Own Laptop, Offline), is another route for text that must not leave the building, but it doesn't make someone else's data yours to use.

Shadow AI, honestly. Shadow AI means AI tools people use at work without their organisation knowing. People use personal accounts at work because it's quick and nobody gave them anything better. Banning it rarely works. What works is a clear rule like this one and one approved tool people can actually use. If your organisation has neither, this book gives you the rule, and T13-L03 · Write a One-Page AI Rule Your Team Can Use Without Asking You shows how to write the one-page policy.

Worked example: two red documents at 18:40

Both cases go through the four quadrants from T01-L01 · From Idea to Working Result: The Four-Quadrant Method.

Lab: the collaborator's manuscript

Structure it. "By 9:00 my PI needs half a page on the collaborator's manuscript: the main claim, the methods, and what they're asking of us. The manuscript is unpublished and was sent in confidence." Colour: red. It's unpublished, it isn't hers, and the email says so.

Understand it. What does the PI actually need? A decision: join the follow-up study or not. Does the institute have an approved tool? The intranet lists a licensed assistant with a data agreement. But the manuscript belongs to the collaborator, and "in confidence" means the collaborator decides who processes it. She emails to ask whether she may use the institute's approved tool. No reply by 19:00. Back to Structure it: "The hard part was never the typing. It's knowing what to look for in forty pages."

Choose tools. Way 2: ask about the form. The public chatbot gets no content at all, so the request is green. The reading stays hers.

Build it. She asks: "My PI must decide whether to join a follow-up study based on a collaborator's manuscript. List the six questions a half-page summary should answer, and where in a typical paper I find each answer." She reads the manuscript with those six questions and writes the half page in forty minutes. What it taught her: next time, ask collaborators up front whether the approved tool is fine for their drafts.

Company: the customer contract

Structure it. "By tomorrow morning, sales needs three terms from a customer contract: payment terms, notice period, liability cap, each with its clause number." Colour: red. It's a customer contract with prices, names and bank details.

Understand it. The company's one-page AI rule lists Microsoft Copilot Chat, used with the work account, as approved for internal and customer documents, but not for employees' personal data. He checks for the green shield at the top of the window, which shows that the work account's protection is on. He also asks himself whether the tool needs the customer's name, the signatures or the bank details to find three clauses. It doesn't.

Choose tools. Ways 1 and 3 together: the approved tool, and only what the job needs. He deletes the signature page, replaces the customer's name with "Customer", and leaves the prices out.

Build it. He pastes the cleaned text and asks for the three terms with clause numbers, quoted word for word. Two come back correct. The payment terms say "see Annex B", which he hadn't included. He opens the annex himself and finds the answer in a minute. What it taught him: a cleaned-up copy can leave out the part that matters. Check what's missing before you trust what's there.

In both cases the answer to "may I paste this?" was no, and the job still got done. The rule didn't stop the work. It changed the route.

What goes wrong

Assuming a paid plan means protection. Symptom: "I pay for Plus (ChatGPT's paid personal plan), so my data is safe." Fix: check whether there's a business agreement. Personal paid plans are still personal accounts. Look for your organisation's approved tool instead.

Assuming a European-sounding name means European processing. Symptom: you pick a tool because the company is based in Berlin or Paris. Fix: the company's address tells you where it sits, not where the model runs. Ask your data protection contact which tools have an agreement that covers where the data is processed.

Uploading the whole PDF "because I only want a summary". Symptom: forty pages go in, including the one page with names and figures, when you needed three clauses. Fix: send only what the question needs. Remove the rest first.

A private account, "just this once". Symptom: the approved tool is slow or clumsy, so you switch to your personal account for one urgent document. Fix: urgency is when mistakes happen. Use one of the three ways, or wait. If the approved tool is really unusable, say so to whoever chose it.

Pasting a colleague's data because it isn't yours. Symptom: "It's her spreadsheet, not mine, so I'm not responsible." Fix: you're responsible for what you paste. Other people's data is red until whoever it belongs to has cleared it.

Taking the names out and calling it anonymous. Symptom: a case description without a name, but with the rare diagnosis, the ward and the date. Fix: check the combination, not just the name. If someone who knows the context could recognise the person, it's still red.

Do it yourself (15 minutes)

1. Structure it (3 min). Open your AI tool's history, the list of past chats that most tools show down the left side, and copy your last five pastes into a document. Only the first line of each is enough; don't copy the sensitive part again.
2. Understand it (5 min). Give each one a colour and a one-line reason, using the table and the one-sentence test. Note which tool and account you used for each. Find out whether your organisation has an approved tool; if you can't find out in two minutes, write down who you'll ask.
3. Choose tools (2 min). For every red one, pick one of the three ways: anonymise, ask about the form, or an approved tool.
4. Build it (5 min). Rewrite each red paste so it becomes green. Try one of the rewrites, and check that the answer still does the job.

If one of your pastes was red and went to a personal account, don't panic and don't hide it. Delete the chat, and tell your data protection contact or your manager what went where. A mistake reported early is easy to handle.

Exit check

What you hand in: a short list of your last five pastes.

• Each paste: what it was (in one line, without the sensitive content), its colour, and a one-line reason.
• Each red paste: your rewrite, and which of the three ways you used.

It passes when a colleague agrees with each colour and no rewrite still contains red material.

Rule to remember

Green is public. Yellow is approved tools. Red is nobody's business but ours.

Details for experts

Checked on 23 September 2026. You don't need this to follow the book; it's for setting things up or answering a colleague.

If these details change, the rule stays the same.

Further reading and tools

Next books

• T11-L01 · Run an AI Model on Your Own Laptop, Offline: a route for text that must not leave your machine.
• T12-L02 · Clean the Copy, Label the Result, Spot the Trap: the same rule once your work reaches other people.
• T13-L03 · Write a One-Page AI Rule Your Team Can Use Without Asking You: turn this rule into a one-page policy for your team.
• T01-L02 · Check AI Output Before Your Team Relies on It: checking what comes back.

Tools

• ChatGPT, Claude, Gemini: Catalogued. Personal plans are fine for green material; their business plans can become approved tools.
• Langdock: Catalogued. A workspace organisations can set up with a contract of their own, as one example of an approved tool.