Conflict is a process in which one party perceives that its interest are being opposed or negatively affected by another party. But conflict is ultimately based on perceptions, so it also exists whenever one party believes that another may obstruct its efforts, whether or not the other party actually intends to do so.
There are lots of conflicts in this movie- The Dark Knight. Characters faced conflict once troubles or problems happened as everyone has their own concern and idea which is sometime the same but sometime not the same. There are also conflicts when corporation or collective decision is needed because of the overlap of personal and group interest.
Conflict between Bruce Wayne and Batman (self-conflict)
Sources of conflict:
A) Incompatible goals:
1) Bruce Wayne believed that he could beat all the criminals and alter the world by donning a mask and a cape to become Batman. However, it is impossible to do this with only personal power and is unreasonable to achieve such goal as world must consists of bad and good guys. 2) Batman wanted to combat crime while keeping a moral attitude and action (which deeply affect his conflict perception). It is impossible to stop people committing crimes through violence but without hurting or killing the criminals once they commit it and without solving the deep-rooted problem. (Bruce Wayne indeed hates Joker and even wants to kill him but he never do that due to his moral values.)
B) Ambiguous rules:
There is no clear and definite rule on how Batman should do to alter the world. All actions are made depended on how Batman values them.
Batman felt extremely angry and nervous when he could not stop Joker from killing one of his friends, Harvey Dent or Rachel Dawes. Batman has to decide who he is going to save.
Quick and immediate decision is needed.
Batman chose to save Harvey as he was...