The Federation Bureau of Planetary Treaties was the agency responsible to conducting planetary treaties between the United Federation of Planets and independant governments. The Bureau of Planetary Treaties attempted for many years to coherce the Gideon Council to allow them to send diplomats to their planet in effort to pursuade the Gideons to join the Federation. Their Council, however, consistently refused the presense of a delegation from the Federation on it's soil, and or any surveillance by the ship's sensors. In 2268, the Gideons finally agreed to a delegation of one, insisting upon it be the Captain of the USS Enterprise.
Following the disappearance of James T. Kirk during beam-down, the Gideons refused to allow any further attempts at transport or searching for Captain Kirk. Spock consulted Starfleet Command for instruction, who in turn, consulted the Bureau of Planetary Treaties. Annoyed with the bureaucratic and diplomatic run-around he was getting from both Starfleet and the Gideon Council, Spock attempted to contact the Bureau directly, but was insistabtly told that he must go through Starfleet channels. (TOS: "The Mark of Gideon")