It’s not a new argument, but the question of Batman’s “no kill” rule came up again this past week when Batman v Superman director Zack Snyder addressed fan complaints about why his version of the character kills.
This comes at time when we’re about to get another movie version of the Joker as well as — in the wake of Ben Affleck’s leaving the DC movie franchise — a new Batman. In the world of superheroes the status quo changes all the time. But one thing always remains consistent. In every version the Joker is a criminal. And so, technically, is Batman.
Source: IGN.com The Screwy Morality of Batman in the Movies