Trump denies authoring or signing any such letter or drawing, claiming the story was "concocted" to "malign" him and that no authentic document exists.
Dow Jones has stated its full confidence in the accuracy of its reporting and vowed to "vigorously defend against any lawsuit."
This legal action follows Trump's public threats against Murdoch's media empire and comes after Murdoch's Fox News recently settled a separate defamation case for a substantial amount.