A treaty signed in 2268 that banned the use of polaric ion energy after a Romulan research accident, recalled by Voyager's crew when they find a planet destroyed by the same technology.
The Polaric Test Ban Treaty was signed in 2268. It followed a disaster at a Romulan research colony on Chaltok IV, which was almost wiped out during experiments with polaric ion energy, a power source that proved far too unstable to control.
The treaty is mentioned in the Voyager episode Time and Again. In 2371 Voyager comes upon a planet whose whole population has just been killed by a polaric detonation, and the crew recognise the signature of the banned technology.
Janeway and Paris are then thrown back to the day before the catastrophe, where they find a society that depends on polaric power and a protest movement that fears it. The treaty serves as proof that the Alpha Quadrant powers had learned the same lesson a century earlier.