The use of electronic monitoring to track offenders has increased by 150% since 2016, while researchers express concerns that technology is “turning the community into a prison”.

Used as a condition of bail, parole or as part of a suspended prison sentence, electronic monitoring – using wrist or ankle bracelets that can track everything from location to blood alcohol levels – has been hailed by state governments and corrective services as a more effective way to manage growing prison populations.

But as the number of offenders placed on electronic monitoring devices grows, there is still no consensus on whether they work.

In June, after a gunman in Darwin killed four people while wearing a GPS bracelet, the NT police chief ordered a review into offenders tracked by electronic monitoring as a condition of their parole.

Data collected by Dr Marietta Martinovic, an expert in electronic monitoring at RMIT University in Melbourne puts the total number of offenders being electronically monitored at 2,500 – a 150% increase in the past three years.

NSW Corrections reported 157 offenders subject to some form of electronic surveillance since September last year, when new sentencing reforms made it easier for courts to add conditions like electronic monitoring to corrections orders. The most recent NSW budget has set aside $2m towards a new GPS monitoring system that would track high-risk offenders.

In Queensland more than 700 people have been fitted with electronic monitors since they began tracking parolees in 2017. A total of 59 were for sexual offences, but more than 300 people are being monitored for non-violent crimes.

Victoria has promised to roll out electronic monitoring for offenders as young as 16.

In the Northern Territory, more than $4m was set aside in 2016 for the expansion of their electronic monitoring program in an attempt to reduce the growing rate of juvenile detention.

“There is certainly merit in looking for alternatives to incarceration,” president of the Criminal Lawyers Association of the Northern Territory (CLANT), Marty Aust said. “We want to see as many people who can be released on parole, released on parole.”

But Aust said the important issue is what – and who – monitoring is used for.

“If a youth offender was subject to electronic monitoring because police wanted to use it as a tool for investigating offences they think they will commit in the future, obviously, one would question the legitimacy of electronic monitoring for that person in the first place,” Aust said.

Others are concerned that the use of tracking devices is a way to widen the net of law enforcement that disproportionately targets Indigenous Australians.

“Because supervision orders and electronic monitoring are viewed as softer sentences than incarceration, the harms associated with them are often invisible,” Associate Professor in law at Sydney’s UTS, Thalia Anthony, said.

Anthony says there is nothing to show that prison populations will drop with an increased use of electronic monitoring.

“In fact, it is quite the opposite,” Anthony said. “You are creating an exceptional set of norms which one population has to live by and the other does not.’’

Researchers at UNSW are similarly concerned that electronic monitoring turns the “whole community into a prison”.

The founder of the police accountability project at the University of NSW, Tamar Hopkins, said there is no evidence that electronic monitoring reduces reoffending or provides a safe and suitable alternative to incarceration.

“There is an incredible stigma around the actual wearing of the bracelet,” Hopkins said. “It may make the offender feel as if they are police property and have a dramatic impact on their emotional and mental wellbeing.

“It can lead to a broad range of social harms. If the person wearing the device feels as if they are being monitored, they will drastically change their social interaction.”

They may feel the need to avoid friends and family because “they do not want them to ‘be known to police’ and cause stops on the street’’.

“The social isolation that comes with being electronically monitored can lead to enhanced feelings of PTSD and potential suicide risk,” Hopkins said.

In 2011, Indigenous man JLG died while being electronically monitored as part of his home detention. The conditions of his bail subjected JLG to random drug tests to identify alcohol or marijuana use which violated his bail restrictions. His partner at the time told an inquest into his death that JLG began to inhale butane in an effort to conceal his substance abuse which he feared would lead to his reincarceration. The abuse of solvents was not listed as a risk on his bail notes despite it being known on his health records.

There have been at least three other occasions in which an offender died while being electronically monitored. Inquests into their deaths revealed they feared the repercussions that would come with violating their bail provisions.

Experts and prison advocates also worry about the kinds of data that GPS monitoring allows corrective services to collect on an offender.

“They can basically create a heat map of people’s comings and goings,” Hopkins said. “People feel as if they will just never be free.”