Persuasion is legal, coercion is not
A surprising amount of behaviour that families find distasteful is perfectly lawful when it comes to wills. A son can lobby his mother for years to leave him the house. A new partner can drop heavy hints about being "looked after". A friend can remind an elderly neighbour of every favour ever done. If the will-maker weighs all of that and decides to act on it, the resulting will stands. English law protects a person's right to leave their estate as they choose, including for reasons others consider unfair, ungrateful or foolish.
What the law does not permit is a will procured by coercion, deception or outright fabrication. Those are the territories of undue influence, fraud and forgery, three distinct grounds on which the validity of a will can be challenged in England and Wales. They are serious allegations with a correspondingly high evidential bar, and courts do not find them proved on suspicion, however strong. This guide explains what each ground means, who has to prove what, and what happens to an estate if a challenge succeeds. It is general information to help you understand the landscape, not legal advice, and it is not a guide to bringing or defending a claim; that is work for a contentious probate solicitor.
Where these claims sit among the grounds for challenge
A will can only be challenged on recognised legal grounds, not simply because someone is unhappy with it. The main validity grounds are:
- Lack of due execution. Section 9 of the Wills Act 1837 requires a will to be in writing, signed by the will-maker (or by someone at their direction, in their presence), with the signature made or acknowledged in front of two witnesses present at the same time, who each then sign. GOV.UK's plain-English summary adds that the will-maker must be 18 or over, of sound mind and making the will voluntarily.
- Lack of testamentary capacity. The will-maker did not have the mental capacity to make a will. Our guide to mental capacity, dementia and will validity covers this ground in depth.
- Lack of knowledge and approval. The will-maker did not actually know and approve the contents of the document they signed.
- Undue influence. The will was procured by coercion.
- Fraud or forgery. The will was procured by deception, or the document or signature is not genuine.
This page focuses on the last two bullet points. For the full menu of grounds and how a challenge proceeds generally, see our hub guide on how to contest a will in the UK.
Undue influence: the coercion test
Undue influence is the most commonly suspected of the three and the most commonly misunderstood. In everyday speech, "influence" covers everything from gentle encouragement to bullying. In probate law, only the far end of that spectrum counts. The courts have consistently held that undue influence means coercion: pressure that overpowers the will-maker's own volition, so that the will expresses the influencer's wishes rather than the will-maker's. The 19th-century case law put it memorably: a testator may be led, but not driven.
The distinction matters because it excludes a great deal of behaviour that feels wrong to disappointed relatives:
| Generally lawful influence | What undue influence requires |
|---|---|
| Persistent persuasion, requests and lobbying | Pressure the will-maker could not resist |
| Appeals to affection, gratitude or family duty | The will-maker's own judgment being overpowered |
| A beneficiary helping to arrange the will | The will reflecting the coercer's wishes, not the will-maker's |
| Opportunity: living with, caring for or isolating access to the will-maker | Proof of actual coercion, not just the chance to exert it |
A frail person can be more easily coerced than a robust one, so the same conduct can be lawful pressure on one testator and coercion of another. But the legal test is always whether free judgment was overpowered in fact, and that is precisely what makes these claims hard.
Why the evidential bar is so high
Two features of the law do most of the work. First, the burden of proof sits entirely with the person alleging undue influence. For certain lifetime gifts and transactions, a relationship of trust and confidence can create a presumption of undue influence that the recipient must rebut. For wills there is no such presumption. The executor propounding the will does not have to prove the absence of coercion; the challenger has to prove its presence.
Second, although the standard of proof is the ordinary civil one, the balance of probabilities, courts require cogent evidence before finding so serious an allegation proved. Coercion usually happens behind closed doors, and the one person who could describe it has died. Suspicion, motive and opportunity, even in combination, are not enough; nor is the mere fact that the will is surprising or unfair. That is why undue influence is pleaded often and succeeds rarely, and why it is frequently argued alongside other grounds, such as lack of capacity or want of knowledge and approval, which have different tests and can succeed where undue influence fails.
Fraud: deception rather than pressure
Fraud overlaps with undue influence but works by deceit rather than force. Two broad patterns come up in the case law. The first is tricking the will-maker about the document itself, for example procuring a signature on papers the person did not understand to be a will. The second, known as fraudulent calumny, involves deliberately poisoning the will-maker's mind against a natural beneficiary with false statements, so that the person is cut out of the will on the strength of lies. In both patterns the will-maker acts freely, but on a false picture that someone else painted dishonestly and knowingly. As with undue influence, the person alleging fraud must prove it, and the courts expect convincing evidence of dishonesty, not just of a falling-out or a changed will.
Want this checked against your specific situation?
Leave your details and a one-line summary. A probate specialist will reply within 24 hours, with no obligation.
Forgery: the will itself is not genuine
Forgery is the starkest allegation: the signature, or the whole document, is fake. A forged will is no will at all, and forgery is also a criminal offence. Section 1 of the Forgery and Counterfeiting Act 1981 makes it an offence to make a false instrument intending that it be accepted as genuine to another person's prejudice, which is exactly what a forged will does to the people who would otherwise inherit.
In the civil dispute over the estate, forgery claims are typically decided with the help of forensic document examination: specialist analysis of handwriting and signatures against known genuine examples, and sometimes of ink, paper and printing. Evidence from the attesting witnesses and about the circumstances in which the will surfaced also features heavily. The standard of proof is again the balance of probabilities with cogent evidence expected, given the seriousness of the allegation. Describing how courts decide these cases is as far as this guide goes; building or answering such a case is squarely a job for a specialist solicitor.
What happens if a challenge succeeds
A successful validity challenge does not rewrite the will in the challenger's favour. It removes the will, and the estate then passes under the most recent earlier will that is valid. If there is no earlier valid will, the estate is distributed under the intestacy rules, which allocate everything by family relationship; our guide to who inherits if there is no will sets out that order. Anyone weighing up a concern therefore also needs to understand the fallback position, because invalidating a will only helps someone who does better under the previous will or under intestacy.
Consider an illustrative scenario. Alan, a retired engineer, made a will in 2019 dividing his £480,000 estate equally between his brother Devan and his two nephews. Five weeks before his death, seriously ill and living with a recent acquaintance who had taken over his affairs, he signed a new will leaving everything to that acquaintance. The family's unease is understandable, but legally the questions are precise ones: was the new will duly executed under section 9, did Alan have capacity, did he know and approve its contents, was he coerced, was he deceived, is the signature genuine? Each question has its own test and its own evidence, and the answers might uphold the will despite the unhappy optics. That precision, and the cost of getting it wrong, is why these disputes belong with a contentious probate specialist from the outset.
Pausing probate while questions are answered
Probate itself does not wait for family misgivings, but there is a formal mechanism to pause it. A person aged 18 or over can enter a caveat at the probate registry, which GOV.UK explains stops all applications for a grant of probate on the estate while it is in force. A caveat lasts 6 months initially and can be extended for a further 6 months, and it can be entered online or by post for a small court fee (check the current amount on GOV.UK, as probate fees changed in 2026). Entering one is a serious step that can trigger legal proceedings and costs consequences, so it should not be used as a bargaining tactic; our overview of probate disputes and caveats covers how the process unfolds. Note that a validity challenge is different from a claim for reasonable financial provision under the Inheritance (Provision for Family and Dependants) Act 1975, which accepts the will is valid but argues it fails to provide properly for someone; that route runs on its own strict time limits.
If something feels wrong
Fraud, forgery and undue influence claims sit at the difficult intersection of grief, family history and hard evidence, and the gap between suspecting something and proving it is wide. If you have genuine concerns about how a will came into being, the sensible sequence is to act promptly, keep any relevant documents and correspondence safe, and put the facts in front of a contentious probate solicitor who can tell you honestly whether the concern has legal legs. Estates in dispute are one situation where professional help is not optional: even for routine estates, our DIY vs solicitor probate calculator shows where the line falls, and any question of coercion or forgery puts you firmly on the solicitor side of it. For the wider process either side of a dispute, our probate guide is the place to start, and we can put you in touch with a specialist who handles contested estates if you need one.