Fourth wall

The fourth wall is the metaphorical barrier between the characters of the story and the audience. The characters are unaware that they are being watched, never address the audience directly and act faithfully according to the rules of the world created for them. Few episodes in the Star Trek Franchise break these rules (thus breaking the fourth wall).

Original Series

Journey to Babel

The conclusion of this episode involves a rare breaking of the fourth wall. (Star Trek: The Original Series 365, p. 219) McCoy was looking slightly to the right of the screen and appeared to be speaking to Amanda and Nurse Chapel when he expresses delight at finally having the last word. However, a more direct breaking of the fourth wall occurred in The Changeling, as Uhura, attempting to read the word "blue" on her viewscreen, turns directly to the camera and the viewers as she mispronounces the word as "blu-ee."

Deep Space Nine

In the Pale Moonlight

Like the episode "Rules of Engagement", this episode comes close to breaking the fourth wall, with Sisko seemingly talking directly to-camera, and hence the audience. However, there is no direct acknowledgment of the audience in the episode itself, instead the viewer merely takes the perspective of the computer to which Sisko dictates his log.

Rules of Engagement

t was Ira Steven Behr who came up with the concept of having the characters speak to-camera, effectively breaking the fourth wall. He was determined not to do "just another trial show" like "The Measure Of A Man" or "Dax", and while trying to decide what to do to make the show stand out, he saw the 1995 Spike Lee movie Clockers. During that film, in a flashback, a character played by Harvey Keitel speaks directly to-camera. Behr thought this was an excellent idea and suggested it to Ronald D. Moore, who concurred, and who wrote it into the teleplay. Moore describes this device as "sort of breaking the fourth wall, but sort of not, because the actors aren't talking to the audience, they're actually talking to someone in the courtroom." (Star Trek: Deep Space Nine Companion) In the sixth season episode "In the Pale Moonlight", this stylistic technique would be taken even further, with Sisko dictating an entire log directly to the camera and audience.

Non episode specific

Captain's Log

"Captain's log," spoken by William Shatner, were the first two words viewers heard on the first Star Trek broadcast, "The Man Trap", on September 8, 1966. Obviously, the "real" purpose of the log is to inform the audience about key plot points; it should be noted that in some of the first episodes of the original series, Kirk's log sometimes broke the fourth wall and described information that neither he nor the crew could be aware of. For example, in "The Naked Time", Kirk describes "... but unknown to us...". There clearly wasn't time to make some other log entries; for instance, in "By Any Other Name", Kirk appears to have made a log entry about a his crew's skulduggery against the episode's villain while he, Kirk, is sitting next to that same villain.

Presumably, these log entries were created after the events had transpired, when the captain had time to update his log, and it was either Starfleet procedure or just Kirk's personal habit to record such logs in the present tense.