A protest sign - ''legal but lethal, we say no, legal highs all must go''- was the message delivered to local and central government politicians at a Dunedin protest synthetic cannabis on Saturday.
About 100 people gathered in the Octagon to protest legal highs.
Concerned parent Wayne McFadyen, speaking at the protest, said his child had struggled with synthetic cannabis addiction and he wanted to challenge Prime Minister John Key to a boxing match and to give the purse to the psychiatric wards full of synthetic cannabis addicts.
''Get in a boxing ring with me.''
Another speaker at the Dunedin protest was Calvin Hooper, who protested outside Cosmic Corner in George St last week after his son was admitted to Wakari Hospital following synthetic cannabis use.
Ayla Espie (17), of Dunedin, speaking at the protest, said she was addicted to synthetic cannabis.
''I don't want to be on it any more. I get so sick of it, and when I don't have it, I don't sleep, I don't eat, I don't do anything. My body doesn't function.''
The crowd applauded when she declared her 26 hours of sobriety from synthetic cannabis and thanked her mother Maria Espie for caring for her as she was ''shaking and sweating'' from withdrawal symptoms.
Dunedin South MP Clare Curran said the Government ''bungled'' the Psychoactive Substances Act.
''It's got holes in it you can drive a truck through,'' she said.
A man in the crowd pointed a walking stick at Ms Curran and yelled ''It's your fault for voting for the legislation ...Where does your conscience lie? You put it on the street.''
Ms Curran said she voted for the legislation because she believed it would stop the sale of legal highs but the legislation had put the blame on city councils and the Government needed to amend the law.
Dunedin city councillor David Benson-Pope said Parliament had ''monumentally'' failed by voting in the legislation.
''The only politician who voted against it was John Banks and he only voted against it because it was tested on animals. I'm more worried about the testing on people and I think it is untenable for it to continue in our community.''
Protests were held in 23 centres from Whangarei to Invercargill. The protests were organised by Tokoroa mother Julie King via a Facebook event page, ''Aotearoa bans the sale and distribution of legal highs in our country''.
In Invercargill, about 170 people rallied against legal highs before marching through the central city and protesting outside the only licensed legal high shop in the CBD.
Emotions ran hot at the rally as more than a dozen speakers, many with first-hand experience of the effects of legal highs on themselves or family members, made it clear they wanted the Government to ban synthetic high products completely.
Labour Party candidate Lesley Soper, who last year participated in regular pickets of the city's herbal high outlets, urged those present to write to their MPs and local councillors making it clear they wanted all products banned.
Later in the afternoon, a small group protested outside the Impuls'd legal high shop in South Invercargill, which had a molotov cocktail thrown through its front window about 1am on Friday.
Although the shop had a closed sign in its front window, owner Warren Skill had a counter, till and stands at the back door so sales could continue.
This angered one protester, who said her 19-year-old son experienced psychotic and violent episodes while on legal highs and was stealing to pay for his next fix.
The arson had not even slowed Mr Skill down, the woman, who asked not to be named, to protect her son, said.