Originally Posted by DACrowe
It would takes months for the Dent Act to pass, if not a year. It would then takes months or even years for it to be fully enacted. In that time, there would be the "war" Foley spoke of. Perhaps Batman played a secret part in it. There were bound to be some copy cats inspired by the Joker. In fact, if there were more theatrically-themed villains (the Riddler? A black mask wearing gangster? Ivy the eco-terrorist? A Lewis Carroll-obssessed predator?), it would explain why nobody bats an eye to Catwoman wearing such a theatrical costume in TDKR. It's par for the course in Gotham post-Joker.
Most of those guys would be sent to Arkham and could be raving about the Batman which Gordon would dismiss. I admit this is speculation, but it logically makes sense more than just quitting cold turkey. Though the movie never explains this aspect.
My head canon. I wish the film implied something similar. It would have only needed but a few lines.