In order to make a valid Will, a person must satisfy the following test:
They must understand that they are making a Will,
They must be aware of the extent of their assets that they are leaving in the Will,
They must be aware of those people that they should morally provide for, especially if they are disinheriting that person; and
That they must not be suffering from any mental condition that has adversely effected their decision.
It can be difficult to prove that someone did not meet this test, and you will have to obtain evidence from various sources. This evidence is usually in the form of witness evidence, or medical evidence, such as a letter from the deceased’s GP.
You may also wish to challenge the Will on the basis of undue influence. This is where you believe that someone may have exerted pressure on the deceased to change their Will. If you are alleging undue influence against someone who had a relationship of trust with the deceased, then it will be for them to prove that the deceased was not unduly influenced. The easiest way for them to do this would be to show that the deceased instructed a solicitor to prepare the Will, and received independent legal advice. Please note that you can be penalised by the court if you allege undue influence without reasonable grounds, and are unsuccessful.