Walter Murch's Rules of Editing

Walter Murch is an American sound designer and film editor, and worked with Francis Ford Coppola and George Lucas in the 1960's and 70's. As well as this, he is a leading author and educator on the topic of film editing, his book 'In the Blink of an Eye' described as a "manifesto for editors".

Although he encourages experimentation in editing, Murch says that there is essentially six categories to consider when editing, and he even provides a percentage to each category to what their value is to the edit as a whole. He says “An ideal cut (for me) [sic] is the one that satisfies the following six criteria at once.” That criteria is... 

1. Emotion (51%)

This is about what emotion you want the audience to feel. 

The audience's emotions and reactions should be of key focus to an editor - will each cut prompt the emotion from the audience that the director and the editors intend for that scene?

The high percentage marks the importance of emotion in the edit. A cut that prompts an emotional response from the audience should take precedence over a cut only meant to preserve the narrative's continuity.

2. Story (23%)

This is asking if the cut does anything to advance the narrative. 

In films, the narrative is the driving force of the film, so making sure each cut is dynamic and advances the story is vital.

3. Rhythm (10%)

This is asking if the cut occurs at the moment that is rhythmically right or interesting, and not jarring to the audience (unless of course this is the intention).

Often if the rhythm in the cut is right, the editing will look natural and the audience will almost be unaware of the edit.

4.  Eye Trace (7%)

This is about how the cut effects the audiences focus in the frame. 

A cut should not disorientate the viewer to the extent that their eyes cannot see the action in the next shot happening. Often actors can make this hard due to their movement in a shot.

If the focus of the next shot isn't radically different to the last before the cut, the cut will not be disorientating, again making the audience unaware of the edit.

5. Two Dimensional Plane of Screen (5%)

This rule refers to the 180 degree rule, and how each edit should follow the axis, the imaginary line that connects the two main focuses in the scene. When filming, the camera should only stay on one side of this axis, and in the edit, consecutive shots should also follow this rule.

6. Three Dimensional Space (4%)

This is about if the cut is true to the physical and spacial relationships within the diegesis (the world in which the film takes place). The cut should make sense in the setting of the scene. 

Murch emphasises that these rules aren't to be strictly followed, and should be used as guidelines when editing. Emotion and story are the top two priorities when editing, however the others often have to be used to achieve this - Murch likens them to “the bonds between the protons and neutrons in the nucleus of the atom.”The last two rules are also much more relevant to classical editing than some editing in film today, as they are much more about continuity and clarity and space, and are to be followed by editors wanting to edit a film where the edits feel truly invisible. Some editors break these rules to give a different effect to their edit, yet ultimately the edit needs to continue to shape the audiences reaction and emotions, and further the narrative.