The UK Ministry of Justice is considering rolling out biometric technology in prisons to cut down on visitors bringing in contraband, reporting that a "successful" recent trial had a deterrent effect.

However, privacy campaigners said news of the trial had come as a "total shock", and watchdogs warned the tech must only be used if there is evidence it is necessary and proportionate.

According to the MoJ, the new tech – from Tascent, FaceWatch, and IDScan – was tested at three prisons in December and January: iris scanners at HMP Lindholme; facial recognition kit at HMP Humber; and identity document verification at HMP Hull.

The aim is to crack down on the amount of contraband brought into prisons. Last year more than 23,000 seizures of drugs and phones were made by prison staff, which was up 4,000 on the previous year.

Most prisons use paper-based verification for documents like driving licences, which the MoJ said were susceptible to fraud, with traffickers using fake documents to gain entry.

The idea is that using biometrics to check the identities of visitors would be more accurate, as well as speeding up the process and reducing the number of people needed – crucial for resource-stricken prisons.

In a canned statement, the MoJ branded the trials "successful".

In particular, it pointed to the deterrent effect of the kit, saying one prison had reported a higher number than usual of "no-shows" after visitors found the software was in use.

However, it isn't clear whether this took into account the fact that some innocent visitors might choose not to attend if they thought they would face biometric tests – such concerns are well-documented in the police's use of facial recognition in live environments.

An MoJ spokeswoman emphasised this deterrent effect was "anecdotal" and that the main aim of the work was to show that the trial was designed to see if the tech could perform the tasks prison staff currently do – effectively, checking visitors' IDs.

Nonetheless, the MoJ said it was looking at rolling it out elsewhere, and the justice secretary David Gauke issued a gushing statement saying that the kit "has the potential to significantly aid our efforts" to fight prison gangs, as part of a "multimillion-pound investment" in security.

Campaigners in 'total shock'

The move comes amid wider concerns about the government's increasing use of intrusive biometric technologies on the public, largely due to the fact it is being used without a legal or oversight framework. More policy details were expected in the Home Office's long-awaited biometrics strategy, but this failed to deliver.

There are, however, various regulators and advisory bodies in the field that the MoJ could have consulted ahead of the trial – which it appears did not occur.

"The use of facial recognition in prisons comes as a total shock to everyone, including the Commissioners who have been tasked to oversee this new surveillance technology," said Griff Ferris, policy officer at campaign group Big Brother Watch.

Indeed, surveillance camera commissioner Tony Porter confirmed to The Register that he hadn't been notified in advance, and was therefore "unsighted" on the technology used, the standards applied, or if any of the 12 principles in the Surveillance Camera Code of Practice were used.

Porter added that he was surprised not to have been consulted given that he has been active in advising police and local authorities in their use of artificial intelligence, and cameras connected to such technology.

But he did stress that he recognised the "very real issues" the Prison Service faces in ensuring safety for inmates and staff, and said he would be writing to the MoJ to offer advice and guidance on future trials.

The Information Commissioner's Office – which launched a formal probe on facial recognition tech last year – didn't say whether it had been consulted. But it did warn that organisations needed to ensure they properly assess the risks of using new and intrusive technologies, particularly involving biometric data.

"The use of this technology in prisons must be carefully considered, with clear evidence to demonstrate that it is necessary and proportionate," the ICO said in a statement to El Reg.

This echoes recent advice from a government biometrics ethics advisory group that said facial recognition tech should only be used if it is proven to be effective and is the only method available.

The MoJ moved to head off concerns by saying that visitors weren't cross-checked against any databases; that data collected was deleted at the end of each day of the trial; and that it had undertaken privacy impact and data protection assessments before the trial.

It added that it would "of course, consult with the statutory and ethical bodies responsible for information and biometrics" before proceeding with any further trials.

But that news of the initial study came via a press release is indicative of observers' concerns about the effect poorly communicated trials could have.

The ICO said the "risk of eroding public trust is great if there is a lack of transparency" about the use of new and emerging technologies.

And Ferris said: "Government seeking public approval for facial recognition cameras in low-rights environments such as prisons is a staggering move, since we know it's also trying to introduce them as a general public surveillance tool."

He added the group was surprised that the government was "continuing to take such an experimental approach to human rights" in the face of legal challenges on its use of the tech by police.

We've contacted the biometrics commissioner Paul Wiles to confirm if he was consulted and will update this article if we receive a response. ®