I just read this BBC story where after a 17 months pilot, the MoJ is going to put tags on thousands of criminals, mostly in preference to community sentences which are obviously expensive to manage.
In the past they used GPS to monitor people on home detention, with alerts being triggered if they leave the proximity of a geofence around their homes.
This is smart because a lot of these criminals are recidivists and many are stupid enough to commit more crimes even while wearing the tags, which also have tamper alarms.
This makes it easy for Police to gather evidence after a crime has been committed and I suspect, based on the numbers they are talking about, that this is likely to be more common than sending Police out when these criminals have breached their parole or sentence conditions.
Why? Because tracking the alarms of thousands of people is also very costly and is often the fatal flaw in GPS tracking systems like this. Budget is generally provided for the hardware, but not enough is provided for a security company or other agency to monitor alarm activations. So most people are tagged, a radius geofence is set up around their place of residence and that’s it until its time for it to come off again.