The Imperium was intolerant of aliens, who they termed gaharey. Alien vessels were required to comply with a strict set of imperatives while traveling through their space, and were subject to regular inspections by heavily-armed warships. Telepaths were especially distrusted by the Imperium, and any found within their territory were sent to detention centers, along with any individuals who may have harbored them.
In 2375, the USS Voyager entered Devore space, carrying a number of telepathic Brenari refugees, who they had rescued from a freighter. The Brenari and the telepathic members of Voyager's crew were hidden in transporter suspension during the inspections. Voyager was able to bring the Brenari to an intermittent cyclical vortex out of Devore space. (VOY: "Counterpoint")