The Guard Belt

One method of managing criminals on Mars is the "Guard Belt," a device that leaves felons floating harmlessly in space. It has not been explained whether the guard belt is used indefinitely on its own, or simply as a means of preventing escapees from Space-Prison to return to the surface of Mars itself. One defective belt caused a Martian criminal to fly through space and land on the planet Earth. It was repaired by the Martian scientist J'onn J'onzz, himself stranded on Earth, who considered using it to return to Mars. Fearing the Martian criminal would rob and plunder an innocent planet if left to his own devices, J'Onzz instead commanded the guard belt to return the fugitive to finish his sentence.

First Appearance: Detective Comics #231 (May, 1956)