The disclaimer originated with the 1932 MGM movie, Rasputin and the Empress, which insinuated that the character Princess Natasha had been raped by Rasputin. Princess Natasha’s character was supposedly intended to represent Princess Irina of Russia, and the real Princess Irina sued MGM for libel. After seeing the film twice, the jury agreed that the princess had been defamed. Princess Irina and her husband Felix Youssoupoff were reportedly awarded $127,373 in damages by the English Court of Appeal in 1934 and $1 million in an out-of-court settlement with MGM. As a preventative measure against further lawsuits, the film was taken out of distribution for decades. Prompted by the outcome of this case many studios began to incorporate an “all persons fictitious” disclaimer in their films in order to try to protect themselves from similar court action.
via All persons fictitious disclaimer – Wikipedia, the free encyclopedia.
and more in this pdf: NZDavisYaleart