Britain is considering a controversial scheme to implant surgically electronic tags in convicted pedophiles amid fears that the extent of the abuse of children has been massively underestimated. The government could then track pedophiles by satellite, with a system similar to that used to locate stolen cars. The tags can be put beneath the skin under local anesthetic and would also be able to monitor the heart rate and blood pressure of the abuser, alerting staff to the possibility that another attack was imminent.