I'm assuming that they will dye her hair blonde...can't remember her description from the script now but I'm pretty sure Anderson was blonde. I saw the title change. At least it's not "Judge Dredd Origins".
Actually, there is a fairly recent JD story with that name
Just be glad they're not making that
into a movie. Not that it was bad or anything, it was actually quite absorbing but if there's one comic book character that shouldn't need an "origin" movie, it's Judge Dredd. It's be like a sequel to the Dollars trilogy where you see the 'Man with No Name' growing up. Characters like Dredd works best with only a vague history IMO.
As for Anderson, yeah, the character has always been a blonde and portraying her otherwise would be like having Mary-Jane as a brunette.