Some offenders will be fitted with anklets that can detect alcohol consumption in sweat - with technicians in the United States analysing results.

New legislation that took effect last week allows police and corrections to require bailed people with abstinence conditions to undergo drug-testing if they have abstinence conditions imposed on them.

A two-year trial will run in the Northern Region, using breath alcohol testing, urine testing and 50 alcohol-detection anklets.

The anklets will be fitted to offenders and take regular readings that are uploaded and analysed every 24 hours. The readings will be analysed by staff in the United States who will look for a confirmed "drinking event" or tamper.

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The anklets work by detecting tiny amounts of alcohol in sweat. They do not record location.

Police Minister Paula Bennett said about half of all crime was committed by people under the influence of alcohol or other drugs.

"This new legislation allows staff to target those with the highest risk of causing alcohol-related harm with more intensive testing and monitoring.

"The main form of testing will be urine testing, and police will use existing breath-alcohol testing technology throughout the country."

Officials say they selected the police Northern Region because it represents more than 40 per cent of all offenders with an abstinence condition.

Corrections Minister Louise Upston said negative tests can provide evidence of sobriety to employers and therefore help them get a job. She said more money was also being invested in alcohol and drug rehabilitation programmes for offenders.

In a submission on the new law, the Law Society said it had concerns about the proposed regime's absence of judicial oversight and its potential inconsistencies with the Bill of Rights.

While Corrections hasn't confirmed who will wear a new bracelet, it's possible one of the country's longest-serving inmates could be considered.

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Dean Wickliffe, 68, has spent more than half his life behind bars and was serving a life sentence for the manslaughter of Wellington jeweler Paul Miet during an armed robbery.

The Parole Board granted Wickliffe parole on May 17. He is not to possess or consume alcohol, illicit drugs or psychoactive substances, will have to submit to drug and alcohol testing if Corrections or police require it.