Unfortunately, the technology, as California implemented it, didn’t work. The case of convicted sex offender Leonard Scroggins shows the system’s problem. Scroggins cut the tracking device off his ankle and allegedly tried to rob or kidnap several women and girls over a two-day period. The device sounded an alarm and parole officers pushed through the paperwork for an arrest warrant, but the process took nearly 24 hours. Even then, police would only learn of the warrant if they picked up Scroggins for some other reason and then checked the appropriate database.
It seems clear to me that an alert from such a device constitutes probably cause for the issuance of a warrant for the arrest of the offender. The tecnology exists to have that happen in a span of minutes, requiring only a judge's (electronic) signature before being communicated to law enforcement who, presumably, would rate this type of case with a fairly high priority. Indeed, the case could be made for automatically generating the warrant automatically, with judicial approval already in place for cases such as this where there was a material violation of the terms of parole/probation.