Using AI to Make Sense of Legal Jargon

A document arrives. Your mother's will, handed over after the funeral. A trust deed from a firm you have never dealt with. Every word in it is an English word, and yet you read a sentence three times and still cannot say what it means.

Most people put it down, feel faintly stupid, and do not ask, because asking feels like admitting you should already know. You should not. Asked what would build trust in a legal provider, 94% of will-writing clients chose "explains things in a way I can understand".

Decoding legal language is one job AI does well, if you point it at the right task. Here is that task, and where it stops.

What AI is good at here

Ask an AI "what does the law say about X?" and you are asking it to recall a rule from memory. That is its worst task: in LegalBench, a large independent test built by legal professionals, rule recall scored lowest of every category.

Ask it "here is a clause, what does it do?" and you are asking it to read what is in front of it. That is among its best. Leading models scored 88% or better on clause-reading tasks in the same study, and in a 2025 benchmark built with eight law firms, document questions scored higher than any other task and beat a baseline of practising lawyers.

Judicial guidance updated in October 2025 says the same: summarising is useful if you check the summary, but legal research is "a poor way of conducting research to find new information you cannot verify independently". Use it as a translator, not a lawyer.

The words that trip people up, in plain English

These turn up most often in the paperwork people bring to us.

• Residue, or residuary estate. What is left after debts, funeral costs, tax, expenses and the named gifts have been paid.
• Issue. Not a problem. Your children, grandchildren and further descendants.
• Per stirpes and per capita. By the branches: if a child dies before you, their share passes to their own children rather than being lost. By the heads: an equal share each.
• Personal chattels. Belongings: furniture, jewellery, cars, pictures. Not money, investments or business assets. The definition changed on 1 October 2014, so older wills may differ.
• Life interest, life tenant, remainderman. The right to income, or to live in a house, usually for life, without owning it. The remainderman takes the capital afterwards. See our Flexible Life Interest Trusts (FLITs) factsheet.
• Discretionary trust. Trustees decide who, out of a named group, gets anything, how much and when. Nobody is automatically entitled to a penny. See Residuary Discretionary Trusts.
• Settlor. Whoever put money or property into a trust. In a will, usually the testator.
• Letter of wishes. A private note left with a will or trust telling trustees what the person would have liked. Guidance, not instruction.
• Executor, administrator, trustee. An executor is named in the will; an administrator appointed by the court where there is none; a trustee holds assets for others, sometimes for decades. See Being an Executor.
• Grant of probate, letters of administration. Both give legal authority over an estate: probate to executors under a will, letters of administration where there is none.
• Attorney and deputy. An attorney is someone you chose yourself, under a Lasting Power of Attorney, while you still could. A deputy is court-appointed after capacity has gone. In America "attorney" means a lawyer. Here it does not.
• Nil rate band, residence nil rate band. The slice of an estate free of Inheritance Tax, currently £325,000, plus a further £175,000 where a home passes to children or grandchildren, tapering above £2m. Both are frozen until 5 April 2031, and that date has moved more than once.

How to ask a question that gets a useful answer

Copy these word for word.

• Paste the clause; do not ask a general legal question. "Here is one clause from a will. In plain English, what does this clause actually do?"
• Name the jurisdiction, every time. "Answer for the law of England and Wales only. If the answer would differ elsewhere, say so." An AI's view of the law, judges warn, "is often based heavily on US and historic law".
• Use ordinary words, not legal ones. "Explain this as you would to a friend who has never dealt with an estate." Plain-language prompts beat technical ones by up to 21 points.
• Set the reading level, but not too low. "Explain it at the level a bright 15-year-old could follow. Do not leave anything out to make it simpler." In a 2025 medical study, accuracy held to about sixth-form level then fell sharply; at a 12-year-old's level, one output in five contained a decision-changing error.
• Ask what it does not know. "List what you would need to see, or be told, before anyone could say what this clause means for my family."
• Ask for the source, then check the source. "Which Act, section or GOV.UK page does each point come from? Give me the link. If unsure, say so." In one 2025 case, 45 citations were supplied; 18 did not exist.
• Ask for questions, not answers. "What are the five questions I should put to the person who drafted this will?" No study we found tests this one.

One rule outranks all of them. Judicial guidance is blunt: anything typed into a public chatbot "should be seen as being published to all the world". Before pasting in a will or trust deed, read Should You Upload Your Will or Trust Deed to ChatGPT?

Where the usefulness stops

An AI can tell you what a clause means. It cannot tell you why your document says it. That is how the law of England and Wales works.

When a court here decides what a will means, the Supreme Court has set out what it looks at: the ordinary meaning of the words, the purpose of the document, the other provisions in it, the facts known when it was signed, and common sense. Three of those five are things a chatbot shown one clause does not have. Where a will is unclear, the Administration of Justice Act 1982 even admits evidence from outside it, including what the person actually intended. In hard cases the answer lives in the file.

The letter of wishes, which it definitionally cannot see

A plan with a discretionary trust almost certainly has a letter of wishes alongside it. The leading English case explains why: the settlor uses one to record "facts, beliefs, expectations, concerns and (occasionally) prejudices about the beneficiaries" which it would be "hurtful, impolitic or simply undesirable" to put in a document beneficiaries can read. Such letters are generally confidential: the deed sets the boundaries of what trustees may do, and the letter operates inside them. An AI sees the skeleton, never the flesh.

It bites hardest with discretionary trusts. Shown the deed, an AI describes a list of "beneficiaries", which sounds like people who are getting something. Being in that class only means you may receive something, if the trustees decide you should. In that same case, the man concerned was told he had no entitlement, and none to information about it.

Nor can it see the file, the rest of the plan (a severance notice, a title restriction, a deed of variation), or the family: who is estranged, who is vulnerable, who should not be handed a lump sum. That is why our Do I Need a Trust? and Writing Your Will: The Decisions That Matter factsheets dwell on circumstances rather than clauses.

Red flags in an AI answer

• American terminology. "Estate tax" is American; here it is Inheritance Tax. An answer using "attorney" to mean your solicitor is not describing English law, and "power of attorney" without "lasting" may describe something that stops working when you need it.
• No mention of England and Wales. If the answer names no jurisdiction, treat it as unplaced. Judicial guidance also flags American spelling and unfamiliar citations "sometimes from the US".
• A confident citation with no link. And never ask the AI to check its own work: asked whether a case it had cited was real, one model said yes, then confirmed on a second look that it "does indeed exist". It had invented it.
• Figures with no date attached. The end of the Inheritance Tax threshold freeze has been April 2028, then April 2030, then April 2031. A figure given without saying when it was correct is not one to rely on. GOV.UK has carried inconsistent dates too.

More on this, including real cases, in When AI Gets It Wrong: Hallucinations, Fake Law and Out-of-Date Figures.

A worked example

The clause Diane gets right. Diane is executor of her mother's will. The residuary clause leaves everything "to my issue in equal shares per stirpes". She pastes it in, asks for the law of England and Wales, and asks in plain English what it does. The answer is correct: her mother's descendants share the estate, and because her brother died first, his share goes to his children.

The clause it gets wrong. Another leaves the house "to my son Michael for life on condition that he permits my daughter Susan to reside there with him". She asks whether Susan has a right to live there. The chatbot says yes, which is what the words appear to say. It is wrong: on HMRC's reading of that precise wording, Michael holds the whole interest and Susan never acquires one. Diane tells Susan she is secure, and Susan turns down a flat.

The AI was not being stupid; it read the clause as almost any reader would. What it could not recognise was wording with a settled, counter-intuitive effect, and it had never seen the file, the letter of wishes, or the conversation behind that drafting. A call to the firm that wrote the will would have caught it. See our Right to Occupy: Property Rights in a Will factsheet. Hypothetical example, for illustration only.

Common mistakes

Asking "what does the law say?" instead of "what does this say?" The first is the question AI answers worst, the second the one it answers best.

Not naming the jurisdiction. Say "England and Wales only", every time, in every new conversation.

Asking the AI whether the AI is right. It will confirm its own inventions with total confidence. Check the source, not the machine.

Feeling clearer is not the same as being clearer. After a simplified explanation, confidence rises considerably more than comprehension does. Confidence, the researchers warn, "is not a good proxy for comprehension".

Acting on the answer instead of asking about it. The best outcome here is not a decision. It is a better list of questions, and the nerve to ask them out loud.

Questions? Book a free call

If you are holding a document you do not understand, bring it to us and one of our estate planning consultants will talk it through in plain English. Pick a time that suits you and your local Squiggle consultant will call you. No charge, no obligation. Book a call or call 01233 659 796.

Talk to Squiggle: 01233 659 796 | hello@squiggleconsult.co.uk | www.squiggleconsult.co.uk | Book a free call: meet.squiggleconsult.co.uk

This factsheet is general information for England and Wales, not legal or financial advice, and the rules can change. Please seek personal advice about your own circumstances. Last reviewed: August 2026.