2. Batman Kills People
Let's accept Batman's schemes against the Justice League as what they were meant to be - extreme-case scenarios, never intended to be put into effect. Ignoring that fact, however, we're faced with the fact that the World's Greatest Detective can't find - or isn't bothered to look for - a way to defeat Maxwell Lord without killing him. To be fair, Lord is killed in the comics, too, but there it's done by Wonder Woman. She's an Amazonian warrior princess, she's often been portrayed as carrying swords. She kills monsters regularly. It would make perfect sense that she not have a problem with murder when faced with the choice with a "him or me" situation, much less with "him or millions". Sure, she was chewed out by other heroes for the decision, but she did what she did, and probably would have done it again if given the chance. In fact, she's right there in the script, being taunted and dared by the villain to take his life, and chooses to remain passive. As I've already mentioned, The Dark Knight came out the same year, and it reiterated Bruce Wayne's absolute refusal to take a life as the central conflict of the character. Here, however, he doesn't even seem to be flustered by the decision, he did what had to be done very matter-of-factly. Gone are the days of Batman, the absolutely morally immovable force for good. Gotham's villains, beware!