In the United States and, subsequently, in Australia the utilization of Global Positioning Systems-Electronic Monitoring (GPS-EM) proliferated in the mid-2000s as part of the populist "tough on crime" agenda. These surveillance-oriented sanctions are applied on serious sex offenders usually post their original sentences. This article critically examines the application and outcomes of GPS-EM sanctions in the United States and Australia. U.S. evaluations have indicated that to be successful, GPS-EM sanctions must contain offender treatment, be appropriately funded, and have an effectively run centralized monitoring center. Evaluative research on GPS-EM sanctions in Australia is yet to be conducted.