It is the job of the (oddly vindictive and gleefully zealous for purely logical folk) Grammaton Clerics to discover and root out those who refuse to medically suppress emotion. One can only assume that they do not get a lot of practice, as Bale, being a Cleric himself is surrounded by them daily, expressing like a man on fire. You can sort of see the problem they had here: "How do we portray convincing conflict between characters when none of them have emotions?", the films makers no doubt said to themselves. "Lets just pretend they don't when they do" was apparently the response.
Quite aside from this problem, the premise isn't really used to say anything about the nature of emotion or humanity, it's just used as the stick the central authority uses on the populous, a crime for which they clearly must be punished. It's not very satisfying sci fi. It's not especially strong action either. While the fictional "Gun Kata" martial art was an interesting (if silly) idea, and there are several good sequences (that inevitably compare unfavourably to The Matrix), it's all ever so slightly too stylised, the precision of the Kata making it all cold and mechanical and heartless.
I get the distinct impression that it is a film attempting to serve two masters and neither can be especially happy with the service. It's a sloppy but curious action film and by Hollywood standards a reasonable attempt at fairly high concept science fiction. It's just unfortunate that that's such a low bar.
