In the Star Trek fictional universe, Section 31 is the name of an
unofficial intelligence and defense organization. It is presented as a
special security operation, manned by United Federation of Planets
citizens, that is not subject to the normal constraints of Starfleet
ethical protocols.  The organization appears, or is mentioned, across
eight episodes of Star Trek: Enterprise and Star Trek: Deep Space Nine.

Overview

Within Star Trek, Section 31 exists outside Starfleet Intelligence's
influence and deals with threats to Earth's and, later, the Federation's
security. Its operating authority stems from a provision of the
Starfleet charter - Article 14, Section 31, from which its name is
derived - that makes allowances for "bending the rules" during times of
extraordinary threats.

Section 31 is comparable to other secret police organizations in the
Star Trek universe, such as the Romulan Tal Shiar and the Cardassian
Obsidian Order. Unlike those organizations, Section 31 does not exist to
enforce government policy or punish traitors, but rather to defend
against external threats. Also, unlike the Tal Shiar and Obsidian Order,
both of whom are greatly feared within their populaces, most people in
the Star Trek universe have never heard of Section 31 and will never
encounter it.

Little of Section 31's history has been revealed on-screen. Since the
concept of Section 31 was created for the Deep Space Nine episode
Inquisition, most references to the organization appear in episodes of
Deep Space Nine, although Section 31 also appears in Star Trek:
Enterprise. Several works of Star Trek spin-off fiction expands on
Section 31's operations; Pocket Books published a four-part series
profiling connections between Section 31's operations and the missions
of James T. Kirk, Jean-Luc Picard, and the crews of Deep Space Nine and
the USS Voyager. These novels explicitly link Section 31 to Fleet
Admiral Cartwright's actions in Star Trek VI: The Undiscovered Country
and Vice Admiral Matthew Dougherty's actions in Star Trek: Insurrection.
Section 31 is also heavily featured in the Star Trek: Enterprise novel
The Good That Men Do, in which Trip Tucker joins the organization after
his supposed "death".

Controversial topics

The implications of Section 31 have been described as "troubling" and
its goals and methods "deeply questionable".  Its methods include
brainwashing, torture, and, as revealed by the end of the TV series,
genocide, the crime that is most opposed by the Federation. The genocide
involves the creation, by Section 31, of a disease designed to kill a
single species, the Founders, with the aim of destroying the
Dominion.

Agents

Throughout the series, several Deep Space Nine officers, including
Captain Sisko, infiltrate Section 31, aiming to obtain from it a cure
for the disease in order to save the life of Odo, but themselves collude
in hiding the crime. This is part of a pattern of overall loss of moral
credibility by Starfleet, in comparison to that which it had in the
original series and The Next Generation.[1] The Deep Space Nine series
and the film Star Trek: Insurrection both "position the Starfleet
authorities in a very dubious light".[1]

Section 31 agents include the following characters:

    * Luther Sloan - Star Trek: Deep Space Nine
    * Harris (portrayed by Eric Pierpoint) - Star Trek: Enterprise
    * Malcolm Reed - Star Trek: Enterprise
    * Novels only:
          o Charles Tucker III (Star Trek: Enterprise; novel The Good
          That Men Do)
          o Admiral Cartwright (Star Trek VI; novel Section 31: Cloak)
          o Admiral Dougherty (Star Trek: Insurrection; novel Section
          31: Abyss)
          o Commander Cortin Zweller (Star Trek: The Next
          Generation;novel Section 31: Rogue)
          o Ambassador Aubin Tabor (Star Trek: The Next Generation;novel
          Section 31: Rogue)
          o Ensign Roberta Luke (Star Trek: Voyager;novel Section 31:
          Shadow)

Appearances

Star Trek: Enterprise

    Although produced later, these episodes come chronologically before
    the above Deep Space Nine episodes.

    * "Affliction"
    * "Divergence"
    * "Terra Prime"

Star Trek: Deep Space Nine

    * "Inquisition"
    * "Inter Arma Enim Silent Leges"
    * "When It Rains..."
    * "Tacking Into the Wind"
    * "Extreme Measures"

Star Trek novels
    Novels are considered non-canon.

    * "The Good That Men Do" (Enterprise novel)
    * "Section 31: Cloak" (Original Series/movie era novel)
    * "Section 31: Rogue" (Next Generation/movie era novel)
    * "Section 31: Abyss" (Deep Space Nine novel)
    * "Section 31: Shadow" (Voyager novel)