Originally Posted by The Joker
What scene are you talking about? The Police didn't have him surrounded. They were all tied up evacuating the hospitals across Gotham and protecting Reese from the rampaging Gothamites.
Before that, after Maroney told Gordon where The Joker would be. Gordon made a comment about getting Lau out alive, Joker either way. Then Joker makes his threats and they totally forget about bringing him in.