Grounds for Contesting a Will — The Five Legal Challenges

Grounds for contesting a will in England and Wales are strictly defined by law, and the courts approach challenges to a valid testamentary document with considerable caution. The right to leave your estate to whomever you choose — testamentary freedom — is a cornerstone of English succession law, and a challenge to a will is not simply a matter of feeling that the distribution is unfair or that the deceased should have provided more generously for particular family members. Dissatisfied beneficiaries must identify a specific legal ground recognised by the courts, marshal appropriate evidence, and initiate proceedings within relevant time limits. Without one of the five recognised legal grounds, a challenge will fail regardless of how unjust the distribution appears.

The five grounds are: lack of testamentary capacity; lack of knowledge and approval; undue influence; fraud or forgery; and improper execution under the Wills Act 1837. Each ground attacks a different aspect of the will-making process, and each requires different evidence to establish. A challenge may also be raised on more than one ground simultaneously, and in practice the strongest cases combine several overlapping allegations — for example, that a testator who lacked capacity also did not know and approve the contents of the will they purportedly signed.

This guide explains each ground in detail, the evidence that is typically required, and what happens if a challenge succeeds. For the procedural aspects of bringing a contested will claim, including how to enter a caveat to freeze the estate, see our guide to contested wills. For how a successful challenge interacts with the administration of the estate, see our executor duties guide.

Ground 1: Lack of Testamentary Capacity

The test for testamentary capacity was established in the Victorian case of Banks v Goodfellow (1870) and remains the leading authority. To have testamentary capacity at the time of making a will, the testator must: understand the nature of making a will and its effects; understand the extent of the property they are disposing of; comprehend the claims of those who might expect to benefit; and not be suffering from any disorder of the mind that poisons the affections, perverts the sense of right, or prevents the exercise of the natural faculties in disposing of property.

In practice, capacity challenges most commonly arise in cases involving dementia, advanced Alzheimer’s disease, serious mental illness, or the effects of medication or alcohol at the time of the will. The burden of proof sits initially with the person propounding the will — that is, the executor or beneficiary who wants the will upheld — to prove that the will was duly executed and that the testator had capacity. If that is established, the burden shifts to the challenger to prove incapacity. Medical evidence, contemporaneous GP records, and attendance notes from the solicitor who drafted the will are all critical evidence in capacity disputes. The Mental Capacity Act 2005 has not displaced the Banks v Goodfellow test for testamentary capacity, though it informs the approach courts take in gathering and evaluating evidence.

Ground 2: Lack of Knowledge and Approval

Even if the testator had mental capacity, a will can be challenged if the testator did not know and approve its contents — that is, they signed a document without understanding what was in it or without truly intending it to represent their wishes. This ground is distinct from capacity: a person may be mentally capable in the Banks v Goodfellow sense while still not appreciating the significance of what they are signing.

Suspicious circumstances that may give rise to a lack of knowledge and approval challenge include: the will was prepared by or at the instruction of a person who takes a substantial benefit under it; the testator was elderly, in poor health, or spoke little English; the testator executed the will very shortly before death; or the instructions given to the solicitor were communicated through an interested third party rather than directly. Where suspicious circumstances are present, the burden shifts to the propounder to affirmatively prove that the testator knew and approved the contents.

Ground 3: Undue Influence

Undue influence in the context of wills means pressure that overbears the testator’s free will and substitutes the influencer’s wishes for the testator’s own. This is a higher standard than the equitable doctrine of undue influence in contract law: in the testamentary context, courts require proof of coercion — that the testator was compelled to act in a way contrary to their real wishes. Mere persuasion, advice, or the natural affection of a carer or family member does not amount to undue influence, even if it influenced the testator’s decisions.

Undue influence is notoriously difficult to prove because it occurs in private and the principal witness — the testator — is dead. Evidence is typically circumstantial: the influencer controlled access to the testator; the testator expressed different wishes to other people; the testator changed their will suddenly and significantly in the influencer’s favour; or the testator showed signs of fear or submission in the presence of the influencer. HMRC and the courts recognise that undue influence claims are fact-sensitive; for more on the evidential requirements, see the guidance on the GOV.UK wills and probate pages.

Ground 4: Fraud and Forgery

A will that was obtained by fraud — for example, where the testator was deceived into signing a document they believed to be something other than a will — is invalid. Similarly, a forged will (one to which the testator’s signature was applied by someone else, or where the document was fabricated entirely) has no legal effect. Fraud and forgery cases are relatively uncommon but do arise, particularly in estate disputes within families where one member had control over the deceased’s financial affairs.

Handwriting experts are commonly instructed to examine the signature on a questioned will and compare it with known authentic signatures from earlier in the testator’s life. Document examiners may also assess the paper, ink, and printing to determine whether the will is consistent with its stated date of execution. Where fraud is alleged, the challenge is treated as a serious matter and the court may order a full forensic investigation before allowing the will to proceed to probate.

Ground 5: Improper Execution Under the Wills Act 1837

Under s.9 Wills Act 1837, a will is only valid if: it is in writing; it is signed by the testator (or by another person at the testator’s direction and in their presence); the signature is made or acknowledged in the presence of at least two witnesses present at the same time; and each witness attests and signs the will in the testator’s presence. Failure to comply with any of these requirements renders the will formally invalid, regardless of how clearly it expresses the testator’s wishes.

Common execution defects include: only one witness; witnesses who were not present at the same time; the testator signing after the witnesses had already signed; or the will signed by someone other than the testator without the required formalities. Temporary relaxation of execution requirements was permitted during the COVID-19 pandemic under the Wills Act 1837 (Electronic Communications) (Amendment) (Coronavirus) Order 2020, but standard execution formalities apply to all wills made outside that period. For guidance on the estate administration that follows once a will’s validity is resolved, see our probate process guide.

Written by Simon Jenkins, SRA 167489, Solicitor at Curtis Legal Limited (SRA 450129). For advice on contesting a will or defending a challenge, call freephone 0800 214 216 or request a same-day callback.