The Echidna Security Team or "E.S.T." was the primary defense and police force of Echidnaopolis. The leader of the E.S.T. held the rank of Constable, who also acted as a liaison to the Brotherhood of Guardians.
While the Brotherhood had often held off the Dark Legion from taking over the city, during Knuckles the Echidna's tenure as Guardian it was the E.S.T. who fended off against the Dark Legion's invasion with assistance from the Dingoes. (KtE: #8, #9)
After the fall of Angel Island to the forces of the Eggman Empire and the Dingo Regime under Kage Von Stryker, the E.S.T. ceased to exist. Many of its members were imprisoned in solitary confinement (like Remington) or sent to concentration camps. Once relocated to Albion, many E.S.T. officers joined with survivors of the Lost Tribe and former members of the Legion-particularly the Frost Legion faction that had once served under Remington-to reform the organization as Albion's defense force. They were forced to battle their kinsmen when the former New Megaopolis Dark Egg Legion invaded Albion, and were having a hard go against the Legion's superior weaponry until Team Fighters arrived to provide assistance. Sadly, a damaged defense system that the Legion had reactivated knocked the new E.S.T., their allies, and their enemies unconscious, and the Echidnas feel prey to Thrash the Devil, who sent them all through a super-charged Warp Ring. (StH: #138, #243, #244)