An international drug policy specialist warns local and central government need to work together for the new legal highs laws to work well.
The Psychoactive Substances Act came into force last year, and requires manufacturers to prove legal highs are safe before they sell them.
At a drug policy symposium in Auckland, international experts lauded the act.
One of the speakers was Ethan Nadelmann, the head of the Drug Policy Alliance in the United States.
Mr Nadelmann says there are still challenges ahead.
"My understanding is that you have a tension going on right now between the national politicians who are facing election and some of the local councils who are really worried about what that means and haven't had the chance to think about it deeply."
Mr Nadelmann says that internal conflict needs to be resolved and the rest of the world is watching how the well the act works.
