A legal bid is under way to get the results of the cannabis referendum thrown out.

A group of more than 350 people is asking the High Court to void the vote on the Cannabis and Control Bill, claiming poor and inaccurate information generated confusion among voters.

It also claims the Electoral Commission reinforced that misinformation.

The bill that would have legalised cannabis was narrowly defeated, with 50.7 percent of voters voting against it, and 48.4 percent for it.

Drug Reform advocate Blair Anderson is one of the people taking the case. He told Checkpoint New Zealanders heard far too much from the "no" vote during the campaign and said there was a failure to correct misinformation.

"We saw ads in the mainstream newspapers of things like dopey dairies, which people will remember had cannabis leaves all over it, with kids on skateboards in front of it.

"There was no such provision within the actual legalisation and control bill to do that. In fact, it was specifically excluded.

"There were the things like 'gummy bears, the menu for kids' and various others that were publicised in mainstream media and social media and so forth.

"Notwithstanding the fact there was also what I call almost stage-managed presentation of people that were obviously smoking a joint in hoodies, whereas in actual fact, we have a mainstream concurrence with the use of cannabis. Our own health and development study here in Christchurch - four out of five respondents in that study have used cannabis in their life. And obviously, most of them have come to no harm," he said.

"There was an expert committee that was assembled, and part of its function was certainly to correct any misinformation."

But Anderson said problems extended beyond what he calls the failure of that committee.

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"Even to the extent that we heard that the Medical Association didn't approve of the bill, and then at the end of the period, just after the bulk of people had voted, had come out and said quite the converse.

"That opportunity to explore these things was not taken by mainstream media for the greater part. We never saw the advocacy, anywhere in the electoral process, for instance, of the Aotearoa Legalise Cannabis Party that had participated in nine MMP elections, and no one was consulted as to what they thought the referendum should look like."

Under the law a judge does have the power to void the referendum, Anderson said.

"The question then becomes, do we have another referendum? There is provision within the Act to have another referendum within six months of his findings. But I think the right thing to do would be for them just to send it to the select committee.

"If the judge thinks this was inherently wrong and it influenced the outcome, he's probably on a bound to say the referendum is null and void.

"It's not the result of the referendum we're disputing. We're disputing the conduct of that referendum and I make that very clear.

"It's quite possible that the High Court judge may look at this and go, 'nope, the Electoral Commission can get a smack over the head for being naughty but the results stand'.

"That's the prerogative of the judge, he will hear the evidence, what's really cute is he can call in the people that were responsible for some of the misinformation and ask them to validate and justify it.

"It's time we all grew up and realised, let's put this to the people - we elected them, they're called MPs. They go on a select committee. The select committee hears evidence.

"That's where it stands and that's putting it to the people. Because the people elected those people to make a decision."

The Electoral Commission has confirmed it has until Friday to respond to the High Court, but declined to comment further to Checkpoint.