The Circle is a secret tribunal authorized by President Tom Zarek. The task of this tribunal is to decide the fate of people implicated as collaborators during the Cylon occupation of New Caprica.
Convictions are for "crimes against humanity and treason". The tribunal's proceedings are apparently limited to the period between the escape from New Caprica and the transition of the presidency from Zarek to Laura Roslin.
The Circle consists of six members and is initially composed of Colonel Tigh, Galen Tyrol, Samuel Anders, Diana Seelix, Jean Barolay, and Charlie Connor, all former members of the resistance on New Caprica. Anders later leaves the group and is replaced by his wife, Kara Thrace.
The members differ drastically in their motivations and behaviour:
- Anders and Tyrol are the most scrupulous members, insisting on proper procedure and clear evidence for convictions. Tyrol is often the last member to cast his vote. Anders drops out in protest against the majority's handling of the case of Felix Gaeta and Tyrol insists on the need to replace him before proceeding.
- Colonel Tigh is less scrupulous and prone to assume guilt by association but - as in the case of Anders' replacement - insists on proper procedure according to presidential decree.
- Seelix and Barolay mostly mirror Tigh's approach but take no stance in the procedural issues.
- The most extreme member is Connor, who is simply out for revenge for his dead son and cares little for procedures. His proposal of summary conviction and execution is vocally (and physically) opposed by Colonel Tigh, who insists that the Circle is "not a death squad".
- Short-term member Kara Thrace, after initial concerns about the legality of the tribunal, quickly votes in favour of Gaeta's execution. She joined the Circle mainly for emotional reasons, seeking retribution for her ordeal on New Caprica by hurting somebody. She assaults Gaeta before his iminent execution but in the process he reveals information that leads to Gaeta's acquittal.
Of the Circle's list of suspects, two cases are shown on screen:
- The Circle convicts James "Jammer" Lyman, a reluctant member of the New Caprica Police, for having participated in killings during a raid and execute him by expulsion through one of Galactica's launch tubes.
- Felix Gaeta, who had served as a presidential aide to Gaius Baltar on New Caprica, is also convicted by the Circle, though without proper evidence, leading to Anders' resignation. Gaeta, unwilling to defend himself, is assaulted by Kara Thrace, which leads to the revelation that Gaeta served as Tyrol's "inside source" during the occupation of New Caprica, passing top-secret information to the resistance. Tyrol convinces the other members of the Circle to acquit Gaeta.
Roslin and Adama are appalled that Zarek would authorize trials without granting the accused the legal representation they are entitled to. Zarek tries to justify this, by saying that the Fleet would be occupied for months or years with proper trials and that he wants to spare Roslin from signing death warrants for the entirety of her next term. The Circle disbands when newly reinstated President Laura Roslin grants a general pardon to all members of the fleet for crimes committed during the occupation. Fifty-six other suspected collaborators on the list are not tried (TRS: "Collaborators").
- Ironically, three members of the circle - Tyrol, Anders and Tigh - are later revealed to be members of the final five Cylons, though they were not aware of it at the time.