Certain people on bail or home detention could be randomly selected for drug or alcohol testing, under changes put forward by Corrections Minister Judith Collins.
Legislation before Parliament this week will enable the Department of Corrections and Police to order community-based offenders and bailees - if they are subject to conditions banning the use of drugs and alcohol - to undergo drug and alcohol testing.
The Government says the change is needed because compliance with abstinence conditions has been hard to monitor, with no explicit legal authority to require testing.
The law change will mean certain people can be directed to undergo testing or submit to continuous monitoring.
In a supplementary order paper released by Collins this week, the legislation would be changed to allow an authorised person (usually a constable) to select in any manner, including randomly, an offender or bailee to undergo testing.
A spokeswoman for Collins said the change was to ensure random testing was an option, while also confirming it was not the only option for testing.
"For example, if a probation officer had reasonable cause to suspect an offender was under the influence when they were prohibited by a special condition, they could then direct the offender to undergo a test to confirm."
About 4000 offenders on community sentences and orders and 15,000 people on bail have drug and alcohol conditions imposed every year.
The New Zealand Law Society, in a submission on the law change last year, said the powers requiring people to be subject to continuous monitoring raised significant concerns.
"Across all groups, but bailees in particular, a requirement to wear a drug monitoring device or alcohol monitoring device is a major infringement of liberty. It will be possible to justify it in some circumstances, but certainly not in respect of all people who are subject to alcohol or abstention conditions," the submission by the society's president Chris Moore stated.
The Drug and Alcohol Testing of Community-based Offenders, Bailees and Other Persons Legislation Bill has the support of Labour, the Green Party and New Zealand First.
Speaking during the bill's second reading last year, Green Party criminal justice spokesman David Clendon said the changes put a level of control on people.
"Yes, it does impose a level of intervention in people's lives, but given the serious nature of the consequences when drugs and alcohol are used unwisely, we think it is appropriate."
There was an upside to the testing, Clendon said, including that test results could be used to prove sobriety in instances such as when a person was trying to get visitation rights to their children.