The prospect of a referendum on legalising cannabis is being welcomed by Peter Dunne who brought in and then banned synthetic versions of the drug.
The referendum is part of the price of Green Party support for the coalition government.
As Associate Health Minister, Mr Dunne pushed for the regulated sale of cannabis and decriminalising other drugs.
He said the Government needs to think about how it would legalise cannabis, before going to a public vote.
"The relatively easy part is having a 'yes, no' referendum, the more challenging part will be how you actually set the system up afterwards. Does it mean for medicinal purposes? Does it mean for recreational purposes and everyone grows their own?"
He said the referendum is a big step forward, but the new government should be prepared to follow through.
"You can't have a situation where you go only half way and say 'well that was all our commitment was to just do a referendum, we're not committed to do anything beyond that because that makes you look silly."