Joseph Labriola, a terminally ill 75-year-old on parole, was visiting a second-hand store in Millis last summer when he received an urgent phone call to go outside.

Labriola, confined to a wheelchair, learned from a state worker tasked with tracking his whereabouts that the GPS monitor strapped around his ankle had lost its signal.

Embarrassed, Labriola excused himself and wheeled out to the parking lot to reconnect. He hadn’t seen the warning blinking light, he said, because it was covered.

“I keep my pant leg over it so nobody else can see it,’’ he said. “It's not something you want to walk around and advertise.”

Parolee Joseph Labriola, 75, rests in his bed in his Milford, Mass. home with a GPS device strapped to his ankle on June 29, 2020. Days before he died, caretakers persuaded state officials to allow them to cut it off. He died in the early morning hours of July 4, Independence Day.
Meredith Nierman WGBH News

This is a familiar drill to many who wear a GPS monitor as a condition of their release from prison. Each day workers at the Massachusetts Electronic Monitoring Program in Clinton respond to about 1,300 alerts from the ankle bracelets, ranging from curfew violations and impermissible travel to charging problems and connectivity lapses, state officials say.

The number of people required to wear GPS monitors in Massachusetts has nearly tripled over the last eight years to about 4,100, including parolees, probationers and those awaiting trial, according to the state Probation Service that oversees the program.

But a growing number of critics question whether the imperfect technology does more harm than good. Some call them a scarlet letter; others, electronic shackles.

“They are expensive and they are onerous for people and they're not actually increasing public safety in any sort of demonstrable way,’’ said Massachusetts Defense Attorney David Rangaviz. “We all tolerate how poorly they work because they are imposed upon people that nobody cares about.”

Launched in 2001, the state program was created as an “alternative to incarceration” with an aim to improve public safety, according to a state website. Supporters say the inconvenience of the bracelets is a small price to pay for freedom. Less than 1 percent of the alerts actually end up resulting in warrants for someone’s arrest.

But those wearing them say the devices can hurt a person’s ability to obtain and keep employment, attend family events or get medical treatment. They need to be charged at least two hours a day, and because they can’t be taken off, the wearer has to sit near a wall socket the whole time — a particular challenge for the homeless. They can be costly; the wearer can be charged a fee of as much as $6 a day, although state officials say this fee is usually waived.

Labriola spoke to WGBH News before he died in July. Convicted of murder in 1973, he always maintained his innocence.

He said he was grateful to be released on the state’s medical parole program meant for the sickest prisoners — but didn’t understand the need for an electronic monitor. Labriola suffered from a myriad of debilitating illnesses and relied on an oxygen tank to breathe.

“When you have a rule like this for a 75-year-old man with heart and lung disease in a wheelchair 24/7 and on oxygen, what's the purpose of this leg iron?” he asked.

GPS device on ankle
As Parolee Joe Labriola rests in his bed on June 29, 2020, the GPS device used to monitor his location is locked to his swollen ankle.
Meredith Nierman WGBH News

The GPS monitor began as an idea thought up by twin brothers completing graduate degrees at Harvard University in the 1960s.

Robert Gable, now a psychology professor at Claremont Graduate University, says the brothers invented a tracking device — at the time using radio frequency — to help juvenile offenders stay out of trouble.

The youths would be rewarded when they were doing what they were supposed to, like attending school and work. Gable says he never meant for the GPS monitors to serve as punishment.

“It has come to be used primarily as a punishment or restraint device,” he said. “That was not our intention.”

Since then, the use of electronic monitors to track accused and convicted offenders has spread across the United States.

Nationwide, the number of people monitored with ankle bracelets and other electronic tracking devices nearly tripled between 2005 and 2015, rising to about 125,000, according to a report by The Pew Charitable Trusts.

Along with an increase in use have come more critics. James Kilgore runs a project called Challenging E-Carceration that opposes the use of electronic monitors. He says there is little research proving they improve public safety and, instead, can hurt people’s efforts to succeed outside prison walls.

Kilgore started studying the topic in 2009 after being released on parole himself with a tracker. He was struck by how it curtailed his freedom, and he spoke to others with similar stories.

“I don't think it is an alternative to incarceration. Rather, it is an alternative form of incarceration,’’ he said. “I think it has some grave dangers for us if we let it continue to expand without a critical perspective.”

Emily Judem WGBH News

Kilgore says the tracking devices are particularly punitive for people on parole — former prisoners serving the rest of their sentences in the community. In 2018, he issued a report called “No More Shackles” arguing parolees shouldn’t have more conditions for their release that could send them back to prison. The vast majority of Massachusetts parolees are sent back to prison not because they committed a new crime but because they violated some provision of their parole, according to an investigation released last month by the WGBH News Center for Investigative Reporting.

In Massachusetts, about 40 percent of the state’s 1,400 some parolees are required to wear GPS monitors, a significantly higher rate than the national average. Across the country, about 2 percent of people on parole and probation are required to be tracked by some kind of electronic device, according to the American Association of Probation and Parole.

Jake Wark, a spokesman for the Massachusetts Parole Board, said in a statement GPS devices are “an effective supervision strategy” for parolees, “balancing the interests of public safety, accountability, and release from incarceration.’’

He said the program provides “a strong incentive to abide by common-sense conditions and stay-away orders,” including curfews and so-called exclusion zones that prohibit parolees from going near victims or other areas they should avoid. He said a GPS device could be used as an alternative to incarceration for a parolee found to have violated a condition of their release.

But even some national advocates of the technology acknowledge problems. Concerned about growing criticism, the American Association of Probation and Parole released a statement in March defending their use. When correctly used, the association said, electronic tracking can promote public safety “more cost effectively and humanely than incarceration.”

However, the association said, devices should only be used for people who really require that level of supervision, with incentives for early removal, and at little or no cost to those wearing them. The association acknowledged that the technology has problems and that research is “somewhat mixed” on its benefits, welcoming more study.

“The technology is not perfect,” said Joseph Russo, who sits on the association’s executive board. “It is an imposition. It is an intrusion. But it's not anywhere near what incarceration is in a variety of different ways.”

"GPS Rules and Procedures for Probationers," provided by a local GPS wearer.

In Massachusetts, 56 employees work at the Electronic Monitoring System in Clinton, about 30 miles from Boston. The center is staffed 365 days a year, 24 hours a day, monitoring people wearing GPS monitors or remote breath alcohol devices.

State officials declined to be interviewed for this story. But WGBH News obtained a 2018 training video where probation officials detailed how the devices work and some of their challenges.

Daniel Pires, who heads the program, said in the video that if people charge their GPS devices for 2 ½ hours a day, they should have up to 40 hours of battery life. He said they discourage wearers to charge while they are sleeping, because they may not get as good a charge. He said the most common warrants, in Massachusetts and across the U.S., are issued against wearers whose batteries run out.

During the training, he said the center receives about 1,700 alerts a day — a number that’s now dropped to about 1,300, state officials say. He said the most common alert is when the GPS devices have cellular access but lose direct contact with a satellite, obscuring their exact location.

“That's obviously because, you know, the majority of the time in the day, you're spending time indoors and obviously not being in clear view of the sky,” he said. “That’s probably the alert that happens the most.”

State officials said that GPS monitors work best to change behavior when they are accompanied by other conditions, like curfews or exclusion zones — just wearing a GPS monitor won’t prevent people from committing another offense, they said. Currently, according to the state, about one in five people wearing GPS are simply being monitored for their movements; they have no specific conditions on their travel.

“A lot of times, especially, I think on conditions of release, it ends up being sort of a catchall and a backstop," Sarah Joss, Probation Service legal counsel, said in the same training video. "There are actually ways to use GPS to work toward rehabilitation and behavioral change. But that doesn't work if GPS is just on without anything else attached to it.”

Over the last several years, the Massachusetts Supreme Judicial Court has ruled on GPS-related cases, limiting their use on certain occasions.

Last year, the state’s top court ruled that Massachusetts can no longer automatically require sex offenders to wear an electronic tether as part of their sentence. The case was filed by Ervin Feliz, who claimed he was subjected to an onerous intrusion of privacy with hundreds of check-in calls from state workers when his monitor lost its signal.

In March, the court also imposed new limits on the use of GPS for people awaiting trial, requiring prosecutors to detail why courts need to know the precise location of defendants. In the ruling, the judges cited the “severe intrusion” of GPS devices, such as wearers needing to find a charger or walk around outside to seek a signal. “These frequent interruptions can endanger an individual livelihood,’’ Justice Frank Gaziano wrote in the ruling.

Joseph Bennett
Joseph Bennett sits for a photo in Roxbury, Mass, on July 30, 2020. Bennett was released from prison in 2019 after a judge vacated his 1997 murder conviction. The 45-year-old, who says he is innocent, is awaiting a new trial. He says almost every week he gets a call from state monitors saying his GPS device is malfunctioning or has lost signal.
Meredith Nierman WGBH News

Joseph Bennett can relate. He says almost every week he gets a phone call saying his device is malfunctioning or has lost its signal. The 45-year-old was released from prison last year after a judge vacated his 1997 murder conviction and is awaiting a new trial to argue his innocence.

Bennett says he’s thrilled to be out of prison but says the GPS monitor adds constant stress to his life. He asked to meet a reporter in a Boston park because it is outside and likely to not cause any problems with his GPS connection.

“They could send the police to my house at any given moment, saying that I was up to something and I can go back to jail just because it is buzzing,” he said. “That's a frightening feeling.”

Boston University journalism students Mikayla Heiss and Matteo Venieri contributed to this report.