The 180 Degree Rule

In film making, the 180° rule is a rule that states that the camera(s) should remain the same side of an imaginary line that is drawn perpendicular to the camera's viewpoint in the establishing shot of the scene.


In the example of an action scene, like a car chase. If a vehicle leaves the right side of the frame in one shot, it should enter from the left side of the frame in the next shot. Leaving from the right and entering from the same side will create a sense of disorientation. If the rule is broken audiences will also lose focus and become confused and they may also miss parts of the film.


The only defence for breaking the rule is 'for effect'. The only way to cross the line without disorientating the audience is to show the camera movement. You cannot cut across the line and once it has been crossed, and the movement shown, you have to stay on that side of the line, unless you show the movement back over it.

In the example from The Lord of the Rings, the 180 degree rule is shown in the schizophrenic conversation between Gollum and Smeagol.