How the tagging system workspublished at 11:11 BST
Dominic Casciani
Home and legal correspondent
Image source, WPA Pool/Getty Images)The system for electronically monitoring offenders - tagging - is one of the most important innovations in criminal justice of this century.
Today there are three types of tags: curfew, location and alcohol. The original tags transmitted a radio signal and communicated with a base station in a home so that the authorities could know if the person was at home and abiding by a curfew.
GPS devices were rolled out in 2018 so an individual could be tracked 24/7. Probation teams can see not only if someone is sticking to their curfew but also going to appointments or classes relating to their sentence - as well as staying out of areas they are banned from.
Alcohol tags, rolled out from 2020, automatically measure and record the level of alcohol emitted by body sweat every 30 minutes. If someone drinks, the tag will know.
The probation team will order the offender to be within proximity of a little box which will read the data regularly during the day.
- As a reminder, a report by His Majesty's Inspectorate of Probation (HMIP) found that almost half of electronic tags used to track offenders' movements are not fitted on time



















