On screen, when two characters or objects exist in relationship to each other, an imaginary axis between them constitutes the 180º line or line of action. In order to maintain geographic continuity and consistent screen direction in film, it is standard practice for the camera to stay one side of this line or axis.
For example, recall the scene where Katniss gives the Mockingjay pin to Prim. The whistle of the Capitol’s train startles the Everdeen women from their preparations. Katniss sits down across from Prim and, along with the reassurance that “as long as you have it, nothing bad will happen to you,” Katniss hands it over and wraps her sister’s fingers around the pin.
Standard film practice would have the line of action drawn between the sisters; Katniss on screen right facing Prim on screen left. When the pin is handed over, the pin would be passed from Katniss’s hand emerging from screen right handing it over to screen left. Yet, in the film during this moment, the camera jumps the line. Viewers see Katniss’s hand emerge from screen left while passing the pin to Prim’s open hand on screen right. This jump reverses screen direction during the gifting of the pin and the proffering of comfort.
[Director Gary] Ross is aware of that the film must allow audiences an understanding of the filmic space, or geography, in which the characters exist. Yet, Ross and his editing team are interested in selectively breaking the rules that provide clarity between the relationships and actions of the characters. By crossing the axis of action, the film formally disorients viewers during moments of significance. Specifically, it would appear that Ross crosses the 180-line whenever Katniss has a poignant moment with someone she cares about.
I initially thought the axis-jumping signified Ross’s commitment to the Michael Bay School of Editing Is Hard I Don’t Wanna, but Robert Chang’s analysis is damn compelling. My only problem with the article is that I wish I’d written it first.