WASHINGTON — The government has buried its nose in Bari Lynne Williams’ personal business.

Almost literally.

Twenty-four hours a day, whether she’s jogging, sleeping or managing a pool hall, Williams wears a high-tech sensor on her ankle that can detect the faintest whiff of alcohol in her perspiration. If she sneaks a drink, the device will know it — and so will a judge, who could put her behind bars for violating a court order to avoid alcoholic beverages.

At $12 a day, the anklet is a bargain, compared with $150 a day to house a minor offender such as Williams in the Loudoun County, Va., jail, and far less than the $24,332 a year it costs Virginia to keep a felon in state prison.

Best of all, backers say, offenders pay the bill.

The biometric anklet represents a recent technological breakthrough whose popularity is gaining as state and local governments search for ways to close budget deficits during the recession. More than half of all states have slashed spending on corrections this year, while some, including New Hampshire, Michigan, California and now Virginia, are closing prisons, releasing some prisoners early or expanding the use of electronic monitoring.

Local governments are also targeting jails for cost-savings.

But the gadget has also stirred “Big Brother” jitters as technological advances make it easier for governments and corporations to keep tabs on people. While law enforcement has been using satellite-based GPS to track offenders’ whereabouts for some time, privacy advocates say the alcohol-monitoring device — known as Secure Continuous Remote Alcohol Monitor, or SCRAM — has taken law enforcement into the realm of continuously and remotely monitoring people’s physical condition.

“We are at a point where no one could have even imagined 15 years ago,” said Albert Lurigio, a professor of psychology and criminal justice at Loyola University who has written about electronic monitoring and privacy since a New Mexico judge, inspired by Spider-Man comics, became the first to sentence a defendant to home confinement with an electronic monitor.

The driver these days is money. The National Conference of State Legislatures lists 28 states that are squeezing savings from corrections by easing harsh drug laws, laying off staff workers or closing prisons. New Hampshire’s governor has proposed using home confinement for habitual drunk drivers, and California lawmakers considered freeing thousands of nonviolent inmates and monitoring them with GPS devices before opting for less-controversial cuts.

People stare at Williams’ chunky gray anklet when she’s out and about, so sometimes she swaddles it in a bandage. On her daily jog around her Ashburn neighborhood, she hides it with Velcro ankle weights or tape. But at other times, wearing a skirt and heels, she almost seems to flaunt the anklet, as if eager to share a cautionary tale.

“Sometimes it’s like being on display, but I tell them what happened, and they listen,” Williams said.

Williams’ troubles began in April 2007. After partying her way through a golf game, she was pulled over by Loudoun sheriff’s deputies on suspicion of drunken driving. They also found baggies with drug residue in her car, according to court documents.

Williams pleaded guilty to drunken driving and drug possession and received two years’ probation. As part of the Drug Court initiative, however, the judge agreed to dismiss the charges if Williams followed a rigorous program involving probation, therapy and compulsory attendance at Alcoholics Anonymous meetings. The program also requires periodic testing for substance abuse.

Until two months ago, Williams was doing fine. Then a sheriff’s deputy paid an unannounced nighttime visit for a breath test. Williams said she was sober. The machine, however, registered a blood-alcohol level of 0.09, a hair over Virginia’s 0.08 legal limit.

Facing six months in jail for violating the terms of the program, Williams instead agreed to wear the SCRAM anklet, whose development began 10 years ago after Michigan law enforcement officials began using GPS devices to track offenders’ whereabouts.

For Williams, the alcohol-sniffing anklet took some getting used to. In the shoe department at Macy’s last month, she became annoyed as three women gawked at her anklet and whispered.

“It’s Gucci,” she snapped.

But she’s also thankful for SCRAM, because wearing the anklet beats sitting in jail.

“I’m not too embarrassed by it,” she said. “It keeps me from drinking, and it’s like training wheels. Soon, I’ll have it off and be on my own, alcohol-free.”

The idea that governments could monitor its citizens’ every move with technology has been the stuff of fiction for decades, and the technology that allows people to create invisible fences for other people has been around for almost 20 years. But in a world with E-ZPass, spyware and surveillance cameras, the notion that law enforcement is increasing its ability to monitor people’s physiological states unsettles privacy advocates.

Mark Monmonier, a professor at the Maxwell School at Syracuse University who has written about sophisticated mapping techniques and privacy, said advances in microprocessors and other technology will almost certainly lead to more intrusive monitoring and potential abuses.

“What is really alarming people is the possible problems, and the problem’s not just Big Brother,” Monmonier said. “It’s a lot of Little Brothers.”