The Enolian Guard was the military branch of Keto-Enol, the Enolian homeworld. They maintain patrol of Enolian space and arrest those whom they believe have broken Enolian law. According to Kuroda Lor-ehn, and as observed by members of Earth Starfleet, the Enolian Guard are known for their severe prison sentences.
The Guard were responsible for sentencing Kuroda and his father to five years at the penal colony of Duronom for stealing latinum. They were innocent of the crime, but no one else could be blamed. Years later, the Guard again captured Kuroda, now a true criminal, and sentenced him to the infamous penal colony, Canamar. Kuroda would escape after seven years before being recaptured in 2152.
In that year, members of the Enolian Guard aboard a patrol ship intercepted Shuttlepod 1 as it was leaving orbit of Keto-Enol. The Guard were under orders to board unfamiliar vessels in an effort to curtail smuggling, which was rampant in those parts. The Enolians discovered apparent contraband aboard the shuttlepod and apprehended the pod's occupants, Jonathan Archer and Trip Tucker. Although Archer and Tucker were innocent, the two were placed aboard a prison transport heading to Canamar. Also aboard that transport was Kuroda, who ultimately broke free and captured the prison transport.
As Kuroda was en route for Tamaal, the Enolian Guard attempted to recapture the transport, intercepting it with three patrol ships. They nearly disabled the transport, but were themselves disabled. Ultimately, all of the transport's occupants were rescued save for Kuroda, who died when the transport ship burned up in a planet's atmosphere. (ENT: "Canamar")