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Lack of testamentary capacity

Understanding the legal position around capacity to make a will is crucial when assessing the validity of a will. In this video, Partner and Head of Private Wealth Disputes, Roman Kubiak, discusses the legal test originally set out landmark case of Banks v Goodfellow (1870) which explored the four key points that determine whether a person has the mental capacity to create a valid will.

The “Banks v Goodfellow Test”

The test for testamentary capacity, as established in Banks v Goodfellow, emphasises four essential elements:

  1. Understanding the act:Did the testator comprehend the nature of making a will and its consequences?
  2. Knowledge of Estate:Did the testator know the nature and value of their estate?
  3. Understanding Consequences:Did the testator grasp the implications of including or excluding specific individuals in the will?
  4. Mental Disorder:Was the testator free from any disorder of the mind that could influence their views on how they choose to dispose of their estate?

Failure to meet any of these criteria can render a will invalid.

Evolution of the law – Key v Key [2010] EWHC 408 (Ch)

The legal landscape surrounding testamentary capacity has evolved with advances in medicine and science. In the 2010 case of Key v Key, a husband’s grief and devastation after the recent loss of his wife led to “dementia-like symptoms” when he provided instructions for a new will just a week after her passing. The court held that these circumstances invalidated the will.

Identifying lack of capacity

Recognising signs of testamentary incapacity after death often involves examining medical records, will-making files and the evidence of individuals who knew the testator. While medical records may provide clues, a comprehensive understanding typically emerges from a combination of various elements.


Capacity is time and issue specific and every case will turn on its own facts and evidence. As such, assessing testamentary capacity requires careful consideration of the Banks v Goodfellow criteria and key evidence.

If you have concerns over a will or are facing a will dispute contact us to speak to one of our lawyers.

Key contact

Roman Kubiak TEP


Roman Kubiak is a Partner and Head of the market leading Private Wealth Disputes team.

He advises across the whole spectrum of private wealth disputes, with a particular focus on high value, complex and cross-border disputes including: trust disputes, breach of trust claims and applications to remove trustees; will disputes, particularly those with an international element; claims under the Inheritance (Provision for Family and Dependants) Act 1975; and claims for equitable relief under proprietary estoppel, constructive trusts and resulting trusts.

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