The Labour Party says the Health Ministry doesn't have the resources to properly manage the Psychoactive Substances Act.
The Act came into effect last year but doesn't put a blanket ban on synthetic cannabis products.
On Saturday, protest marches were held in 22 areas throughout the country calling for a complete ban.
Labour's Associate Health spokesperson, Iain Lees-Galloway, says the ministry doesn't have the resources to deal with complaints in a timely manner, so many products which should be removed, are staying on the shelves.
"I have no doubt that there are products that are out there legally for sale right now that pose more than a low level of risk and under the law they should be banned straight away."
Associate Health Minister Peter Dunne says the ministry has appointed additional staff and he's satisfied it has the resources to do the job.
Meanwhile, Julie King who is an organiser of one of the protest's calling on the Government to ban synthetic cannabis says the next step is to take the battle to Parliament. She says they'll now focus on an official petition which they plan to take to Parliament in May.
