Many contract sweepers have been experimenting with tracking via global positioning systems (GPS) for years - some even spending thousands of dollars to develop their own sweeping-focused GPS. And depending on which sweeping contractors you talk with, GPS can be a business-saving technology that improves job quality, employee performance, profits and customer confidence. It might be expensive, and if you pay for too-detailed a service, you might be wasting money, but sweepers (and owners of other construction equipment, and insurance companies) have come to accept that GPS is valuable in pinpointing a truck or an action at a specific time and location. Now the Illinois State's Attorney's office agrees, and they have a judge who supports them. Last week Robert Anderson, a judge in Illinois' DuPage County, ruled that evidence of a defendant turning his GPS switch on and then off can be used in his trial. According to the Illinois State's Attorney Robert Berlin, defendant Eric Hanson turned his personal GPS system off before slaying four family members in September 2005 - then turned it back on while he was driving to the airport after the four people were killed. The GPS evidence will be used both to convict Hanson of the crime and to demonstrate premeditation. Robert Miller, Hanson's defense attorney, argued that the GPS information should not be admitted to trial and that even if admitted it does not prove "consciousness of guilt."