Suppliers of synthetic drugs would face eight years' jail under a bill that has passed its first reading with the support of National and NZ First, the first time this term that the parties have joined forces.
Lewis Jones, who lost his 22-year-old son Calum to synthetic cannabis addiction last year, was on hand to see National MP Simeon Brown's bill pass its first reading and referred to select committee.
The bill passed this afternoon with National and NZ First in support, while Labour, the Greens and Act opposed it.
Speaking on the bill, Brown paid tribute to Jones and called suppliers of illegal psychoactive substances "despicable merchants of death".
"Because of how easy it is to get these drugs, within days of leaving rehab, [Calum Jones] was dead."
The toxicity of illegal psychoactive substances varied, he said.
"When you light up, will it be experiencing a high, or will it be the last thing you ever do?"
Police Minister Stuart Nash said in response that it was a needless tragedy to lose someone to drug addiction.
"I cannot imagine what it would be like to lose and son or a daughter to a drug overdose."
But he said 91 per cent of prisoners will have a mental health or addiction issue in their lifetime, and the issue was much bigger than simply increasing penalties.
He said it was a political move to use the term "soft on crime".
"Please don't say the only way to stop this is to lock people up. That is the language of a community and a society that has lost its compassion."
Earlier Jones delivered a 1200-strong petition to Brown in front of Parliament, flanked by National MPs Maggie Barry, Simon O'Connor, Tim van de Molen and Matt King.
Jones said he represented those "who haven't got a voice, the ones who have passed away, and the ones still being neglected and looking for help".
"My son actually died from his internal organs disintegrating [from drug abuse], and I didn't see it from the outside. It puts a lot on me because I didn't actually know what was going on."
Jones said tougher penalties was one part of the solution, along with increasing health services, which failed his son.
"I fought like hell to get him into a drug detox centre ... I had to lie through my back teeth to get him into it.
"They let us down. I thought he was in a safe place, but a week before he died ... he was thrown out for a person who needed assistance who was an alcoholic. In that week, he passed away."
There have been 25 deaths believed to be linked to psychoactive substances.
Brown also called for select committee inquiry into how the system deals with those suffering with addiction to synthetic drugs.
The bill would also bring the maximum penalty for supply in line with the penalty for supplying Class C drugs, such as cannabis.
Labour and the Greens opposed the bill because they don't believe it will reduce drug harm.
"All it does is imprison people and add to the already ridiculously overpopulated prisons," Green's justice spokeswoman Golriz Ghahraman said.
"It's just a very expensive, useless policy."
Drug Foundation executive director Ross Bell said the bill would have "zero impact" as there was no evidence tougher penalties affected drug harm.
But New Zealand First leader Winston Peters said the bill would see far fewer people die on the streets.
"These [suppliers] are merchants of death and the number of people who've died is clear evidence of that."