The inverter was a device used by Ansata separatists on planet Rutia IV to carry out terrorist attacks. Based on the Elway Theorem, it operated by transporting a subject from one place to another through a dimensional shift. Although the inverter made it impossible for the Ansata to be tracked, it caused severe cumulative distortions in the cellular chemistry of anyone using it, a process which, with prolonged use, could prove fatal. The Ansata activated the inverter by utilizing an armband which consisted of a subspace field coil with an isolated power source.
In 2366, the Ansata kidnapped Doctor Beverly Crusher from the USS Enterprise-D in the hopes that she could develop a way to reverse the deleterious effects of the inverter. A Rutian team detected faint nuclear vibrations when the Ansata utilized the inverter, suggesting an application of the Elway theorem. With this knowledge the Enterprise crew developed a method whereby an adaptive subspace echogram could be used to track the terrorists' movements. Later, the Ansata used the inverter again, this time to mount an attack on the Enterprise and kidnap Captain Picard, in order to use him as a bargaining chip to leverage Federation involvement in their conflict with the Rutians. Eventually, the Enterprise crew was able to use the echogram to track the Ansata to their underground base and rescue Doctor Crusher. (TNG: "The High Ground")