RFID Monitoring. I first saw this tech years ago on 60 minutes or 20/20. The technology is catching up with itself and there are moves to really start an implantation plan in the mainstream. Not so much on the locator end, but in medical applications sector. Transporting your medical history files and I D. Registering changes in bodily conditions (Diabetes glucose) and other conditions.
I think that it could be likely that convicted individuals could be monitored with these devices. Concerned parents in many countries are, for safety, implanting their children. Individuals at risk also use the tech. With protocols, military, and business can find enormous value in the tech.