Section 31

Section 31 is a covert secret police organization in the Star Trek universe, within Starfleet Intelligence, which deals with threats to the security of the United Federation of Planets. It was apparently formed in 2161 by provision in a little-known part of the UFP charter, Section 31, from which they derive their name. It might be compared to the Romulan Tal Shiar or Cardassian Obsidian Order, but operates much more clandestinely and effectively.

They defy the principles of the Federation in order to protect them, which is one of the reasons why Section 31 is not officially sanctioned by Starfleet, and its very existence is not acknowledged openly.

Section 31 unsuccessfully tried to recruit Julian Bashir on repeated occasions.

During the Dominion War, among other questionable actions, they engineered a genocidal virus to exterminate the Founders of the Dominion. They also meddled with Romulan internal politics and were said to have had an agent on the Klingon High Council.