Electronic monitoring has very important utility, but it's not without its flaws. According to a number of law enforcement personnel and leaders I've spoken to, whether it concerns parole or other circumstances, it works; however, there are limitations. Sometimes the battery runs out. Sometimes it's defective. It is not a perfect solution, but it is, I think, one of a number of tools that are used.
I would say that one of the more effective tools I have seen was developed by the Toronto Police Service, and I believe it is now being expanded across Canada. It relates directly to monitoring. It's basically a bail dashboard that enables local police agencies to track those who are on bail, for example, and enables police officers to go to their houses or to do random checks, which was not possible given the volume. This, in fact, gives a really good sense of what's happening across the city. If law enforcement is in a particular area, they can go and check on two or three houses where there may be people who are on bail.