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How to Fact-Check an AI Answer: A Checklist
In 2023, lawyers brought six court decisions to a US court that do not exist. A chatbot made them up. Below are six steps, the red flags and a ready-to-copy prompt so you never repeat that mistake. It takes about a minute.
Six cases that never existed
A passenger sued the airline Avianca, and the case was heard in federal court in New York (Mata v. Avianca). The plaintiff's lawyers cited precedents a chatbot had found for them. Six of them were invented: the case names, the docket numbers and the quotes from the rulings. On 22 June 2023 the judge fined the lawyers and their firm $5,000.
The most telling part: one lawyer asked the chatbot whether the cases were real. It said yes and added that they could be found in legal databases. Asking an AI whether it is right tells you nothing. The check has to come from outside.
Six steps to verify
You do not need to check every word. Check what you are going to rely on: a fact for a document, a number for a report, advice you will act on.
Ask for the primary source
Type: "Where is this from? Give me a link to the primary source." A primary source is the law itself, the study, the official site or the company report. A blog summary or a news story quoting someone else does not count.
Open the source yourself
Follow the link. Does the page exist? Is it the right document? Find the exact passage with in-page search (Ctrl+F). Sometimes the link is real but says nothing about your fact.
Match numbers and dates
Check every figure, amount, percentage and year against the source. Be extra careful with numbers that look too precise. If the data is a few years old and the answer says "now", it may be out of date.
Check the quotes
Paste part of the quote, in quotation marks, into a search engine. If the phrase cannot be found word for word anywhere, it is a paraphrase, not a quote. Do not put it in a document or post as direct speech.
Separate knowledge from guesses
Ask: "Mark what you know for sure and what you are assuming." AI writes with the same confidence about checked facts and invented ones. This request helps you see where the answer rests on a guess.
Find a second source
Check the key fact independently: a regular search, the official site, or another AI with web search turned on. Two independent sources agree, so you can rely on it. They disagree, so keep digging.
When not to trust the answer yet
- The link does not open, or lands on a home page or a 404 error.
- A perfect quote with a page number that you cannot find anywhere.
- Suspiciously precise numbers with no source, like "exactly 37.4%".
- A confident tone where experts disagree or the data changes often.
- The AI agrees with how you framed it: ask "isn't it true that...?" and it says yes.
- An author, journal or law you have never heard of anywhere else.
Law, health, money
The checklist lowers the risk, but it does not turn an AI into a professional. When a mistake costs your health, your money or a court case, the AI answer is a draft of questions, not a decision.
Law
Statute numbers, articles, case law. Check them against your country's official legal database and decide together with a lawyer. This is exactly where the lawyers in the Avianca case went wrong.
Health
Diagnoses, doses, drug combinations. AI can help you prepare questions for your doctor, but it does not replace one. Never change a treatment because a chatbot said so.
Money
Taxes, loans, investments, contracts. The rules depend on the country and the year. Check with the tax authority or regulator website and talk to a financial adviser.
The "Check yourself" prompt
Paste it after any important answer in ChatGPT, Claude, Gemini or another AI. It does not guarantee the truth, but it shows where the answer rests on a guess and what to open yourself first.
Check your previous answer.
1. Split your claims into three groups: "sure, with a source", "assuming", "don't know".
2. For every fact, number, date and quote, give the primary source: title, author or organisation, year and a direct link. If there is no exact source, say so: "source not found". Do not invent links.
3. Mark what I should double-check myself first.
4. If you find a mistake, fix it and tell me exactly what changed.Still open the links yourself. An AI can fix one invention and make up another in the same reply.
Tick as you go
Checking catches mistakes. Can you get fewer of them?
The checklist works after the answer. The next step is understanding where inventions come from and asking in a way that leaves the AI less to guess.
- How AI works and why it is confidently wrong
- How to write prompts that lead to fewer guesses
- How to get answers based on your files, not the model's memory
- Common beginner mistakes and data safety
Service names and their modes, such as web search, change over time. This description is current as of October 2026; check what the service offers today. The facts about Mata v. Avianca come from the court's decision of 22 June 2023.
Want to understand AI, not just check it?
Everything in the block above is covered in the AI Fundamentals course. It is made for people who do not code: from how models work to using them every day.
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