They're designed to keep the public safe and save local law enforcement money.
In a time when new technology seems to debut every few months rather than every few years, GPS tracking devices are helping the criminal justice system keep an eye on convicted criminals and even those awaiting trial.
It played out in a Kankakee County courtroom last month.
An Iraq war veteran had his bond finally set 27 days after being arrested May 1 for allegedly stalking an ex-girlfriend.
Justin L. Sikma, 36, of Bourbonnais, was released on a $30,000 bond by Kankakee County Circuit Court Judge Clark Erickson.
It is the second time he has bonded out in the past year following a stalking arrest.
Sikma must again wear a GPS monitoring device that helps police keep tabs on him and ensure he doesn't violate a judge's order of staying 500 feet away from his ex. He's also back to wearing a bracelet that monitors his drinking.
Sikma, whose two cases still are being prosecuted, is the only one currently being monitored by GPS in Kankakee County, said Tom Latham, director of court services and probation in Kankakee and Iroquois counties.
He also is one of three people being monitored for alcohol.
"It is something I'd like to see used more by the courts," Latham said.
The American Civil Liberties Union, which keeps a close watch on privacy issues, supports GPS trackers.
Ed Yohnka, director of communications and public policy for the ACLU of Illinois, said that while technology increases privacy concerns, this type of GPS monitoring is more about crime prevention and cost efficiency.
The average cost of housing an inmate in the state's prisons is more than $30,000 with jail stays not far off. That means holding people in custody while they await trial can cost taxpayers far more than the $1,400 cost of the device, which the defendant is expected to pay.
Of course, not everything goes smoothly. Last year, the Los Angeles Times reported the probation department there was becoming inundated with false alerts. The newspaper cited a New York judge's report that a dozen of the nation's federal court districts ignored short-term alerts, effectively rendering the program obsolete.
In March of this year, the U.S. Supreme Court ruled as unconstitutional a North Carolina law allowing the state to track for life serious sex offenders with a GPS device.
At the time of his arrest, Sikma, who has been diagnosed with post-traumatic stress disorder, was wearing a tracking device for a 2014 stalking charge involving another ex-girlfriend.
Assistant State's Attorney Scott Ripley told the judge that the women were not opposed to a bond being set for Sikma as long as the judge ordered the tracking device.
Sikma served in the Marines for four years.
"He wanted to fight for those who died or were injured," said his father, Mark Sikma. "He said what those terrorists did wasn't right."
SIkma's mother, Ruth Chamness, said her son's temperament changed after serving in Iraq.
Randy Chamness, Sikma's stepfather, said alcohol has played into Sikma's trouble.