When Mrs. Helen Dow Peck died in 1955, she left almost her entire estate to "John Gale Forbes," whom she met via Ouija board. Which is to say that John Gale Forbes was not a corporeal entity. Mrs. Peck's surviving (flesh-and-blood) relatives sued, arguing, in essence, that Mrs. Peck was clearly nuts. The court eventually agreed and voided her will. This has established the legal precedent that ghosts can't inherit money. Read more about the case here.