A person making a Will must have the requisite mental capacity to do so. Testamentary capacity is the term used to describe a person’s legal and mental ability to make a valid Will.
A person needs to understand the nature and effect of making a will, and the extent of the property/assets they are leaving in their Will. They should understand the impact the will has on the people who may inherit and must not have a ‘disorder of mind’.
If that is not the case, the Will may be invalid, in which case a previous Will takes effect. If there is not an earlier valid Will, then the person’s estate will be distributed according to the Intestacy Rules. These rules set out who will inherit where there is no Will.
If you think that the person was living with a medical condition when they made the Will, which might have impacted on their capacity (for example, dementia or Alzheimer’s disease) then you may want to explore contesting a Will.