In the heat of an argument last spring, Khyla Mason raised a handgun into the air on a neighbor’s porch. She was acting in self-defense, she said, and never fired, but the confrontation was captured on video, and some children were nearby. Ms. Mason wound up in a St. Louis jail charged with unlawful use of a weapon.

Just a few years ago, someone facing the same charge in St. Louis was likely to pay a small bond and resume life as usual until trial, local attorneys said. But Ms. Mason, who was then 21, was released from jail with a box the size of a deck of cards strapped to her right ankle. It tracked her every move.

For weeks, the device alerted officials each time she missed her court-imposed curfew or left her house without approval. Sometimes, she was buying food or diapers for her 2-year-old son, or taking him to the hospital, she said. After more than two dozen violations, she was sent back to jail.

She remained there for a month.

More and more defendants across the country are being placed on electronic monitors, part of an ambitious effort to prevent overcrowding in the nation’s jails and keep people from being imprisoned while awaiting trial for minor offenses.

Like courts in Baltimore, Dallas and Los Angeles, the St. Louis city circuit court is among those that have embraced electronic monitoring as a powerful reform of the cash bail system. The number of new monitors activated here more than doubled from the first half of 2021 to the first half of 2024, when it surpassed 550, a New York Times analysis found.

But in that time, St. Louis has had to grapple with some unforeseen complications — including technological mishaps, privacy concerns and high costs — that offer lessons to other courts. More significantly, the devices are now worn by hundreds of people who most likely would not have stayed in jail anyway.

The Times analysis found that about three-quarters of the people monitored in St. Louis in the first half of 2024, including a small number ordered to download monitoring apps, were charged with misdemeanors or lower-level felonies such as unlawful gun possession, driving while intoxicated and third-degree assault. In the past, people facing those kinds of charges would generally have been offered a cash bail, four local criminal attorneys said.

The devices have subjected some defendants to more scrutiny than those individuals would have otherwise faced. They have also made it more obvious that the defendants were accused of a crime, and several said that having a visible monitor cost them a job or made it hard to attend school or care for a child or an older relative.

In a statement, Joel Currier, a St. Louis city circuit court spokesman, acknowledged that monitoring was “an imperfect tool,” but said that the court’s program balanced “the rights of the accused as well as the safety of crime victims and the community.”

Michael K. Mullen, a retired St. Louis city circuit judge who supports monitors, said the devices were better for defendants than jail.

“That’s what they have to be reminded of when they come in front of me,” he said.

But Matthew Mahaffey, who runs the city’s public defender office, which represents people who cannot afford attorneys, said that monitoring was too often required of people who posed no flight risk or threat to public safety.

Making matters worse, he said, the devices have occasionally malfunctioned and provided inaccurate readings.

“Until it gets cleared, it looks like a violation, which can put the client in a tricky spot,” Mr. Mahaffey said, adding that defendants had been sent back to jail or issued harsher sentences as a result.

Research has also shown that electronic monitoring can lead to isolation and prejudice from landlords and employers, said Kate Weisburd, an expert on surveillance and technology who teaches at U.C. Law San Francisco. She raised further concerns about privacy.

“As there is a growing appetite to end incarceration, there’s this knee-jerk reaction to want to substitute incarceration with something,” she said. “We can’t just strip people of their privacy rights the moment they are arrested for a crime.”

Dead Batteries and Missed Curfews

Last year, The Times sat in on dozens of pretrial bond hearings, which are held to determine whether a person who has been arrested will be released or held in jail, and interviewed more than 20 people who wore ankle monitors. The charges against them ranged from harassment and property damage to domestic assault.

James Neal wore a monitor for about six months last year after he sped away from a traffic stop. He was later charged with fleeing, resisting arrest and drug and firearm possession, court records show.

Mr. Neal, 42, was not allowed to carry a weapon because of a past felony conviction. He said he kept one anyway because of the city’s high crime rates.

Once the monitor was installed, Mr. Neal had to charge the device by connecting it to an outlet and sitting tethered to the wall for hours at a time. That was especially difficult while he was looking after his young son, he said.

Mr. Neal received violations because the battery died and because he left his house without the court’s permission, court records show. Once, he was cited for spending two nights at his mother’s house after a death in the family, the records confirm.

Mr. Neal pleaded guilty in July and was sentenced to probation.

Ms. Mason, who was sent back to jail last summer for the violations her monitor flagged, fell behind on her rent while she was incarcerated, she said. By the time she was released in August, she had been evicted from her north St. Louis apartment. She was in the second trimester of a new pregnancy.

Ms. Mason said the monitor affected her life in other ways. After wearing it to the hospital where she worked as a dietary worker, she lost her job. The hospital said she was let go because of poor attendance, but Ms. Mason said she had covered her absences with sick time.

In the months that followed, she said, potential employers zeroed in on her ankle at job interviews.

“I can’t really get a job or any good opportunities because people instantly judge me,” she said in October.

In December, a judge reduced Ms. Mason’s felony charges to a single misdemeanor. If she stays out of trouble for two years, the remaining charge will be expunged from her record.

She had the ankle monitor removed two weeks before giving birth in the new year.

‘Least Restrictive’ Conditions

The St. Louis city circuit court began using devices with GPS technology to monitor a small number of defendants about a decade ago. At first, the initiative drew criticism because of how it was funded: The private company running the program charged defendants installation and surveillance fees, and those who could not afford those fees could be sent back to jail.

The program remained small for years. But in 2019, amid a wave of bipartisan bail reform policies, the Missouri Supreme Court directed judges across the state to seek out alternatives to incarceration for defendants who could not afford bond.

In St. Louis, the number of people ordered to wear monitors spiked, data shows. The numbers held steady during the pandemic, when public health officials called for fewer people to be held in jails, and then surged when Gabe Gore — who cast himself as a law-and-order candidate — became circuit attorney and ramped up prosecutions.

Mr. Currier declined to make Judge Christopher E. McGraugh, who became the court’s presiding judge in January, available for an interview.

In many ways, the St. Louis court has done more than most to make the monitors less disruptive to defendants’ lives. It now covers the costs of monitoring for those who cannot afford to pay, something many other courts across the country, including the neighboring St. Louis County circuit court, do not do. In recent months, the city’s circuit court has paid for almost 90 percent of people who were being monitored, data shows.

In addition, the court’s pretrial services office offers bus passes and mental health and shelter referrals to people with pending cases, Mr. Currier said.

Total Court Services, a company based in Michigan, is the court’s contractor for monitoring services. It rents a small office across the street from the courthouse; there, four or five employees keep tabs on more than 400 defendants at a time.

The vice president for sales and marketing, Jason Tizedes, said the company was trying to make monitoring less intrusive. It recently released a smartphone app that judges in the St. Louis city circuit court have started to use in a limited number of cases.

“If folks are lower risk, you don’t want to overmonitor them,” Mr. Tizedes said in an interview. “If you oversupervise, overmonitor people that don’t need it, it’s essentially setting them up for failure.”

As for the privacy concerns, Mr. Tizedes said, the company shares people’s location data only with court officials and law enforcement officers who have warrants. He blamed the job loss and the discrimination people with monitors sometimes face on unsympathetic employers.

David D. Hemphill, who works in home renovation, said he felt that discrimination while wearing a visible monitor last year. After landing fewer contracts than he expected, he fell into a depression.

Mr. Hemphill, 38, said that he had been arrested after failing to pull over for a traffic stop and leading the police on a 30-minute chase. He said that the officer who had initiated the stop was a neighbor, and that he did not trust the police.

Four months after the arrest, the charges against Mr. Hemphill were dropped, he said. But in that time, Mr. Hemphill became increasingly paranoid. His monitor beeped constantly and issued loud voice alerts. Sometimes he did not know whether the noises meant that the equipment was faulty or that he had unknowingly violated the terms of his release.

Once he began wearing his monitor, he noticed just how many of his co-workers on construction sites were wearing the same kind of device. He started talking to them about their experiences and realized that many felt the same as he did.

“Each violation plays on your mental,” he said. “You don’t know what the outcome is going to be. These people have your life in their hands.”

A Record Budget

Though many see it as a reform, electronic monitoring has drawn wide-ranging criticism both in St. Louis and across the country.

Blake Strode, the executive director of ArchCity Defenders, a St. Louis civil rights law firm that has challenged the use of cash bail and inhumane jail conditions, called the city circuit court’s monitoring program “an incarceration scheme” that set people up to be jailed for technical violations.

Mr. Strode acknowledged that judges used cash bail less frequently now, and that the jail population had shrunk. But electronic monitoring starts punishing people as soon as they are charged with a crime, he said, not after a finding of guilt.

“We should ask whether that trade-off is worth it,” Mr. Strode said.

The policy has also faced a different critique: that letting people accused of crimes await trial at home undermines public safety. Some critics have also said that court officials and prosecutors have not been aggressive enough in punishing people for violations.

In St. Louis, that argument gained traction in 2023, after a man awaiting trial on robbery charges ran a red light and seriously injured a teenage pedestrian. The defendant, Daniel Riley, had amassed dozens of GPS violations before the crash, but was never ordered to appear in court over the infractions. The city’s circuit attorney at the time, Kim Gardner, resigned amid the controversy.

National proponents of electronic monitoring like Carl Wicklund, a former executive director of the American Probation and Parole Association, continue to see the value in the system. But Mr. Wicklund said that people with the devices must be able to hold jobs, secure housing and be involved with their families, churches and communities.

Without those things, he said, defendants become “higher risk, because they have nothing to lose.”

According to the St. Louis circuit court’s 2023 annual report — the most recent it has published — nearly 87 percent of defendants who wore monitors completed their pretrial periods without a new arrest. The figure was nearly the same for defendants who awaited trial at home without monitors. (The court cautioned against using the statistics to draw conclusions about the effectiveness of monitoring, saying that the figures did not account for factors such as age, criminal history and substance abuse.)

Court officials’ investment in the program continues to grow. This fiscal year, the city budgeted more than $850,000 for the initiative, a record high for St. Louis. Budget documents show the court is on track to spend more than $1 million on the initiative.

In the spring, the court plans to solicit proposals from contractors interested in providing monitoring services after its current contract expires. Mr. Tizedes said Total Court Services was likely to submit a bid.

Justin Mayo contributed reporting. Susan C. Beachy contributed research.

This article was reported in partnership with Big Local News at Stanford University.

ABOUT THE ANALYSIS

To calculate the number of new ankle monitors activated in St. Louis, The Times analyzed hundreds of pages of monthly invoices that Total Court Services sent to the St. Louis City 22nd Circuit Court from October 2020 through June 2024. The invoices, obtained through a public records request, show how much Total Court Services billed for each defendant (identified by case number) who used 24/7 ankle monitoring services. The Times excluded defendants monitored only via the company’s smartphone app, CourtFact, which has a limited GPS component. The invoices specify start and end dates, as well as whether the court or the defendant was responsible for payment.

To calculate the share of monitored defendants who were charged with misdemeanors or class D or E felonies, The Times analyzed the court’s monthly pretrial data reports. The reports, which are available online, include monthly counts of defendants released from jail with GPS monitors broken down by class of charge.

Discrepancies between the invoices and the court’s reports are because the reports indicate the month judges ordered defendants to wear GPS monitors while the invoices indicate when the monitors were activated, and the two dates can be different. Additionally, pretrial data reports included defendants released with CourtFact smartphone monitoring in the totals. Beginning in June 2024, the reports included only defendants with GPS ankle monitoring.