Evidence of mental capacity can come from lay witnesses and medical experts.
The usefulness of medical experts can sometimes be limited because they will often be seeking to retrospectively comment on someone’s mental capacity after their death.
Arguably, witness evidence – from people who spent time with the testator – can be much more persuasive.
In particular, real-world examples of what the testator could or could not understand when the Will was executed can often be decisive.
However, there can be competing accounts about the extent of a testator’s comprehension.
If so, the court will be tasked with weighing up the relevant evidence and making a determination on whether or not the deceased had testamentary capacity.
In some cases, there is medical evidence about a testator’s mental capacity from the time when the Will was signed off.
In such cases, the medical evidence can prove to be of substantial value, but much will depend on the expertise of the author of such evidence.