The use of drugs offering so-called 'legal' highs will be banned in New Zealand unless manufacturers can provide clinical evidence that they are safe.
Associate Health Minister Peter Dunne described the move as a knockout blow to the market for products such as synthetic cannabis and legal "party pills", which mimic the effects of drugs like ecstasy without using illicit substances.
Dunne said current legislation was failing because as soon as regulators banned a synthetic drug, manufacturers simply tweaked its formula slightly and relaunched it in the marketplace.
"The new law means the game of catch-up with the legal highs industry will be over once and for all," he said.
At the moment, authorities must prove a synthetic drug is harmful before ordering it off the shelves.
Dunne said that under the new law, all synthetic psychoactive drugs will be illegal until their producers can provide clinical proof, such as toxicology reports and evidence from human trials, that they are safe.
"Companies wishing to sell these products will need to apply to this regulator with scientific data similar to that which is required for the assessment of new medicines," he said.
The department of health estimated that carrying out clinical tests would cost manufacturers up to NZ$2.0 million ($1.6 million) for each synthetic drug, effectively deterring them from trying to sell such substances in New Zealand.