What are they and what can they be used for? A Probate caveat is a type of document that is lodged with the Supreme Court that prevents a grant of Probate or Letters of Administration from being granted. A caveat cannot be lodged after a grant of Probate has been made and if it has, it will serve no purpose. It can be used to challenge the validity of a Will in instances where there may be doubt about the execution of the Will. It can also be used whether there are concerns about an executor or administrator's ability to carry out the wishes of the deceased person or concerns as to whether they are the most appropriate person to fulfil that role.