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Australia needs to chill out about marijuana and take its cue from US states Colorado and Washington by legalising the drug, the HEMP Party says.

Help End Marijuana Prohibition (HEMP) Party president Michael Balderstone says Australia needs to spark up a debate and a referendum over marijuana laws.

“If we had a referendum here and had a proper open discussion – a month-long discussion – I would think it would pass,” he told AAP.

“Our stance is that the law is a crime.”

Mr Balderstone argues that the law might also be stopping tax revenue.

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In Colorado, the sale of up to 28 grams – or an ounce – of weed became legal on January 1.

State officials anticipate sales will generate about $US67 million ($A75.55 million) in annual tax windfall.

But critics say it will turn the Rockies into the stonies by creating a culture of “pot tourism”.

Sean Azzariti becomes the first person in the U.S. to legally buy marijuana for recreational purposes: http://t.co/1PFcRuWi8h — POLITICO (@politico) January 2, 2014

Mr Balderstone does not deny the drug has been linked to psychosis, but argues the health damage is less, on average, than that caused by tobacco and alcohol.

“Absolutely, it can (cause psychosis),” he said.

“It’s not for everybody, I agree.”

But he maintains people who get high are more likely to stay in than go out and cause trouble.

The Australian Drug Foundation warns there is no safe level of drug use.

“Those with a family history of mental illness are more likely to also experience anxiety, depression and psychotic symptoms after using cannabis,” the foundation says on its website.

“Psychotic symptoms include delusions, hallucinations and seeing or hearing things that do not exist or are distorted.”

In May a NSW parliamentary committee recommended legislation to allow medical use of marijuana by patients with a terminal illness, and for those who have moved from HIV infection to AIDS.

The recommendation, rejected by the government, called for patients to have up to 15 grams of dry cannabis or the equivalent amount of other cannabis products and equipment.

A study published in medical journal The Lancet in 2012 showed 15 per cent of Australians and New Zealanders between the ages of 15 and 64 in 2009 used marijuana that year.

That figure was higher than usage in the US, where 11 per cent of the population got high that year.

Australia’s pot laws vary from state to state – the drug is illegal in NSW, Queensland, Victoria and Tasmania.

Possession of marijuana mostly attracts fines in the ACT and NT, while WA users receive mandatory drug diversion counselling if caught with 10 grams.

Marijuana for medical use is legal and regulated in 19 US states, and has been allowed in some cases for the past 20 years.