Corrections wants the ability to monitor offenders' sweat for drugs and alcohol through its electronic monitoring bracelets.
The department will switch to new equipment next month, after signing a $180 million contract with UK company, Buddi.
When seeking bids for the contract, it requested technology that could continuously monitor a wearer's perspiration.
Programme Director David Grigg said the new bracelets would not track wearers' sweat at this stage, but Corrections wanted the option in future.
"Being able to detect alcohol and drugs allows Corrections to enforce the integrity of a sentence, order or electronically monitored bail conditions, but also helps identify increases in risk and provides the necessary support for people with substance abuse issues," Grigg said.
"The Buddi Smart Tag does not monitor the wearer's sweat levels or take bodily measurements other than a wearer's location. Again there is the opportunity to enable us to leverage off future technology enhancements within this agreement but as we transition to a new provider and new equipment we are not introducing this at this stage."
Corrections piloted sweat monitoring in Auckland and Northland between 2017 and 2019.
The trial found offenders whose sweat was monitored were sober and drug-free over 90 percent of the time, and that those people were more likely to get treated.
However, Victoria University of Wellington criminologist Liam Martin said monitoring sweat was too invasive.
It was likely the technology would enforce bias against those who were already disadvantaged by the criminal justice system, Martin said.
"The idea of people walking around with bracelets monitoring their sweat, you know, how far does this go? We know who it's going to target.
"It's a definite area to watch because it's an area of expansion in criminal justice right now."
Canterbury Howard League for penal reform president Cosmo Jeffery was on electronic monitoring in the early 2000s.
The technology would only help to reduce drug and alcohol use if the wearer was willing, he said.
"My feeling is you can only support someone if they give their consent to it. You can't force someone to go, for example, to Alcoholic's Anonymous."
Jeffery said he would want to see more data before any such monitoring was undertaken, including how many people on electronic monitoring use these substances and break their sentence, bail or parole conditions.
Human rights lawyer Douglas Ewen said the move aligned with a 2015 law change allowing monitoring of drug and alcohol use for some offenders.
The technology could legally only be used on those who had had relevant conditions imposed, he said.
However, Ewen said he could foresee a situation where Corrections collected the information automatically, which would be a breach of privacy.
"Corrections ought to be really quite careful in when this kind of operational facility is used, unless they've got specific authorisation in terms of a court order or a parole board term.
"Even if they have the capacity to collect it, they really shouldn't."
On the other hand, people subject to the testing may find the technology less intrusive than current monitoring methods, as it was done remotely, Ewen said.
He questioned whether the funds would be better spent on drug and alcohol treatment.
"Slapping someone with a don't consume alcohol condition, if they have got an alcohol problem is trying to achieve by way of court order something that requires varying degrees of intensive therapy and treatment.
"It is optimistic to say the least, if not actually naive."
Deputy Privacy Commissioner Liz MacPherson said Corrections would need to assess whether sweat monitoring was a proportionate response in light of the identified privacy impacts.
If it decided to go ahead, Corrections would need to do what it could to mitigate the privacy concerns, she said.
RNZ
