180 Degree Rule - Dark Knight

The 180° rule is a basic guideline in film making that states that two characters (or other elements) in the same scene should always have the same left/right relationship to each other. If the camera passes over the imaginary axis connecting the two subjects, it is called crossing the line. The new shot, from the opposite side, is known as a reverse angle.

Whilst this rule is meant to be stuck to, Christopher Nolan controversially broke this rule in The Dark Knight in the interogation scene between the Joker and Batman. In this scene the director shows us that the Joker and Batman are similar people and that the Joker still has some sort of control even though he is being interrogated.  

In addition the conversation between the two characters implies that the rule is being broken e.g. 'tonight you're gonna break your own rule'.