It's kinda funny that Batman doesn't kill, but Superman does.
Batman didn't seem to have any qualms with machine gunning the shit out of the guys in the Tumblers and trucks in TDKR
(one of which directly showed the bullets from The Bat killing the driver of the truck), and he caused Talia's fatal crash. Desperate times call for desperate measures.
Plus, his whole Ra's al Ghul "I won't kill you, but I don't have to save you" line was a copout on his part. If you sent Gordon to blow up the tracks and then stand by when you could save Ra's from the crash, you most certainly did kill him.
Mind you, I don't have a problem with either.