Re: How long did Nolans Batman actually fight crime?(SPOILERS)
Two things to consider for me;
The Dent act. Do people seriously believe the Dent act was written, established, enforced and worked overnight? This would have taken some time, and the city could not have become clean in the space of a few weeks. I would speculate that Batman was phased out over a 1-2yr timespan, still fighting for that time whilst being chased by the authorities. It's certain that Gordon, or whoever, would have had task forces after Batman. Gordon even says,'They'll chase him'. Of course he may not be speaking literally here, but logically let's assume that he was.
War hero. Foley says early on that Gordon was a war hero. Well, there was certainly no evidence of any type of war in BB or TDK, unless he s being entirely metaphorical. Again, would like to think that the repurcussions of TDK were heavily felt afterwards, and that there was a time of chaos and conflict for an established time, something like 2 years. Then Bruce comes to the realisation that Batman is no longer needed, and coupled with his body falling apart, put's the cowl away. He rigs the cave up with computers etc and does some behind the scenes surveillance and work for a few more years, then stops entirely for the remainign 2 yrs and basically degenerates into the Bruce we see at the start of TDKR.