Synthetic cannabis dealing is an issue across the Mid-South Canterbury district, police say after catching suspected dealers with 20 bags in Waimate.

On Monday, Waimate police stopped a vehicle occupied by four people, including a 15-year-old youth, and seized 20 bags of synthetic cannabis.

Waimate sergeant Mike van der Heyden said the drugs, which as of last May were not available legally, were divided into small bags.

The four were arrested, but the synthetic cannabis will be tested before any charges are laid.

Mid-South Canterbury Area Commander inspector Dave Gaskin would not confirm where the investigation into the incident was at but said it was a problem across his district and not just in Waimate.

Marijuana smokers aged between 18 and 45 are wanted for a university study on brain activity.

The only catch is that cannabis users who sign up for the study will have to lay off the 'wacky backy' during the trial.

Auckland University scientist Dr Bruce Russell said the research will examine whether regular recreational cannabis use affects decision-making.

He'll be pitting students with little or no history of cannabis use, against those who've been smoking it at least twice a day.

For around $20 an hour students will have their brain activity monitored to compare activity associated with thought processes when they're sober.

"We're not giving anyone any drugs — we just want to see what the effects might be," said Russell.

A contribution from the New Zealand Drug Foundation

In 2013, Professor Wayne Hall presented a paper at an International Cannabis Policy Symposium hosted by the New Zealand Drug Foundation in Auckland. It was a review into 20 years of existing research into cannabis titled "What has research over the past two decades revealed about the adverse health effects of recreational cannabis use?".

So far, so uncontroversial. 

A Hawke's Bay mother wants people to know what drove her to break the law by giving her daughter cannabis oil.

Toni Matich told TV One's Sundayprogramme she had no regrets because she eased her daughter's suffering.

Ms Matich said she had "spectacular" results after supplying her 17-year-old daughter, Monique, with cannabis oil to alleviate the pain from enduring more than 1000 seizures a day.

Monique was diagnosed with Dravet syndrome, a rare form of epilepsy that begins in infancy.

Every seizure carries the risk of causing severe brain damage.

Ms Matich was told by doctors she had exhausted all treatment options and her daughter had only months to live when she began researching medicinal marijuana.

How severely people are dealt with for possession of illegal drugs or drug utensils is to be reviewed - with officials to focus on whether action is proportionate to how much harm an offence causes.

Associate Health Minister Peter Dunne has released the 2015-2020 National Drug Policy, which could significantly reform the treatment of drugs such as cannabis.

Mr Dunne said three words - compassion, innovation and proportion - were of the utmost importance when developing drug policy.

The policy has been hailed as hugely significant by the NZ Drug Foundation, who say it signalled an armistice in "The War on Drugs".

"[It] all adds up to a signal that changes need to happen with how we deal with low-level drug offending," said executive director Ross Bell.

A former licensed retailer of synthetic cannabis has been sentenced to three years four months imprisonment after a series of police raids netted drugs with a street value of more than $1 million and $181,000 in cash.

David Ronald Young, 52, appeared in the Rotorua District Court on Wednesday where he was sentenced on charges of possession and supply of synthetic cannabis and the class C drugs, TFMPP and BZP.

Judge Philip Cooper said the case involved "very large quantities [of drugs] with very large returns".

Young, the owner of Rotorua retailer Skingraft, was formerly licensed to sell synthetic cannabis until the law change on May 8, 2014, which made the sale of the product illegal.

Although the deabte over medicinal cannabis debate is currently one of the hot moral and social topics, it misses the real issue. It's part of a wider subject.

It's a question of what we're doing on this planet. We're not here to pay taxes, or to be righteous, or even necessarily to be healthy. We are on this planet to live. To experience this reality and what it has to offer.

We already know that different people like to experience different things. Some people like to spend time with their close family. Some people like to drink alcohol. Some people like to make millions of dollars trading.

It's a big world, and there's room for a lot of different behaviours here.

As marijuana use becomes more acceptable, researchers are scrambling to answer key questions about the drug.

In 2013, Beau Kilmer took on a pretty audacious head count. Citizens in the state of Washington had just voted to legalize marijuana for recreational use, and the state's liquor control board, which would regulate the nascent industry, was anxious to understand how many people were using the drug — and importantly, how much they were consuming.

Self-medicating with cannabis is not going to harm you, says Jeanette Saxby. Getting arrested for having cannabis is far more damaging.

I have been using cannabis since I was 17. I was first prescribed anti-depressants after a bad spell of gloomy at 14. I am now nearly 50 and have spent several years at university to better understand marijuana use in New Zealand.

I had a bad fall from a horse in 2003 and damaged my pelvis, back and hip. I haven't had a day free from pain in over a decade.

At the time I had my accident I was working at Odyssey House in Christchurch as I am a qualified drug and alcohol counsellor with a degree in education.