The best bet would probably be an ankle bracelet like the kind used by the courts for home arrest, except with a few twists.
First, a service would monitor the bracelets, and the individual wearing it would have to carry a cellphone, so that they could randomly call him to get a GPS and voice confirmation of their location.
Eventually, such a system could integrate in sound and video, both randomly and if the person wearing the device wanted to record and transmit.
Collars. Locking collars that only service provider has the key to.
Start ringing people’s next as soon as they can walk. Include an electrical shock that can be remotely operated by law enforcement.
It’s for the children.