He said police officers already used discretion and followed clear guidelines to determine whether a prosecution was appropriate and whether it was in the public interest.
"Police officers are already shouldering too much of the burden when it comes to caring for people who need professional help for mental health issues and drug and alcohol addictions. For this new initiative to be more than lip service to drug reform, the rehabilitative services that Ministers Clark and Nash refer to need to be in place before this law comes into force," he said.
A statement from New Zealand Police said that officers, guided by the Policing Act 2008, the Solicitor-General's prosecution guidelines, and Police's Prevention First operating model, used discretion on a daily basis in dealing with a range of matters, including the
possession and use of drugs.
"Applying this discretion increasingly includes the use of alternative resolution options including pre-charge warnings, Te Pae Oranga, and referrals to health and other support services.
"Police will work closely with partner agencies to develop clear guidance for
dealing with those in possession or using drugs, as legislative details are
confirmed."
National Party leader Simon Bridges said the Government was giving police more leniency when dealing with people buying and using hard drugs including P (methamphetamine), heroin and cocaine.
"If the Government wants to decriminalise drugs it should try and win the support of Parliament and the public, not simply skirt the process by instructing police to avoid the law. Instead it's outsourcing the responsibility for serious decisions on drugs to police," Bridges said in a statement.
But Professor Doug Sellman of the National Addiction Centre said that even though the moves essentially sanctioned what police were often doing already it was "arguably the most important step a Government has announced in gaining better control over illicit drugs for over 50 years".
"It is very hard to imagine a situation where a therapeutic approach would not be more beneficial than criminalisation. However, there needs to be easily accessible therapeutic options available to the police for this to be enacted," Sellman said.
Selah Hart of Hāpai Te Hauora, Māori Public Health, said it was "huge for Māori".
"Our people have suffered disproportionately under an antiquated approach to drug use in Aotearoa which has seen people who use drugs treated as criminals and not as people who have a right to health care and treatment."
The Addiction Practitioners' Association said it was great to see the Government acting decisively after more than 50 deaths from synthetics use this year.
"However, addiction practitioners also hope that police will take into account the reality of life for many synthetic drug users when they use their discretion and consider using the diversion option.
"For example, people sleeping rough who are using synthetics will find it hard to access services and are more vulnerable to falling through the cracks of any diversion system," association executive director Sue Paton said.