Potent synthetic cannabis products are continuing to appear on shop shelves despite the Government's attempts to outlaw them.

The continued appearance of the products has seen New Zealand's drug laws labelled a joke by both supporters and opponents of cannabis law reform.

Media attention pushed the fake dope into the spotlight last year and prompted the Government to amend the Misuse of Drugs Act to provide a temporary ban on new psychoactive substances for up to 12 months.

Associate Health Minister Peter Dunne said it had resulted in 20 substances being banned, which has seen up to 50 products withdrawn from sale.

But the move has not stopped similar products, which give users the same high as smoking dope, appearing on shop shelves.

The Taranaki Daily News is aware of one dairy selling two different brands of the synthetic cannabis including Tai High – Hawaiian Haze.

The product's packaging states it was manufactured in January 2012 and lists chemicals it does not contain but doesn't say what it does contain.

Jamie Dombroski, who stood for the Aotearoa Legalise Cannabis Party in last year's general election, said the products showed prohibition didn't work.

"The drug laws are a joke as it is. As far as I'm concerned, you can't stop people from taking drugs in any way, shape or form," Mr Dombroski said.

"Things like this just prove the point."

Mr Dombroski said he had tried one of the synthetic products and confirmed it gave a comparable high to cannabis.

"It's slightly different in its own right but a very similar experience," he said.

However he would still prefer the real deal to the chemical taste of the fake dope.

"At least you know where it's come from and what's in it. I'd prefer to be able to go to a cafe and buy something that's from nature."

Detective Senior Sergeant Grant Coward said he wanted to see all product containing cannabinoids outlawed.

"To put it bluntly, it is ridiculous, that they can continue to sell that sort of product when we spend hours and hours enforcing the cannabis laws," Mr Coward said.

"Anything that's going to alter the mind of a rational person is something we would not like to be seen being sold."

Mr Coward said the Government's temporary legal measures banning some of the products were inconsistent and not working.

"As far as I'm concerned, there should be one law for all of them, not one law here and another product very similar in its makeup and it is legal," he said.

"If there are others escaping the loophole, then obviously there is some work that needs to be done to ensure that they are in the same category as the ones that are banned."

New Plymouth MP Jonathan Young said he had spoken to Mr Dunne and had asked the Health Ministry to investigate.

"If applicable, to gazette these substances and have them removed from New Plymouth dairies," Mr Young said. "The minister has assured me that if a psychoactive substance is found for sale, the ministry will move immediately to have it removed from the shelves."

Mr Young called on dairies to act responsibly and show a sense of community responsibility by removing the products.

"These products are generally untested and we do not know the long-term effects of their use."

He said the process to deal with the substances was complex and it was important to get it right. "The products change frequently and new ones are put on the market with a different ingredient or two. The temporary class drug orders mean we can capture them all."