A person making a Will must have testamentary capacity at the time that it is made (or at the time that the instructions are given) in order for the will to be valid. The test for establishing whether a testator has mental capacity to write a Will was established in Banks v Goodfellow.
John Banks, the Will maker had been confined to an asylum for some years. After discharge, he continued to suffer from delusions; notably, he was of the belief that a man called Featherstone Alexander was persecuting him.
Banks prepared a Will leaving his estate to his niece, Margaret Goodfellow. Margaret died intestate, two years after Banks and her estate passed to her half-brother, who was not related to the Will maker.
John Banks junior, the son of the Will maker’s half-brother, then contested the will. He argued that Banks senior did not have testamentary capacity. The Court found that Banks’s will was valid, and although he suffered from mental illness which caused delusions it did not influence his decision regarding who should benefit from his estate.
It is important to note that it is a low threshold test, as it is the belief of Courts and Governments that a person’s right to make a will should be upheld whenever possible. This is reflected in the idea that there may be a ‘lucid interval’ where a person suffering from a mental illness may have will-making capacity.