MPs are unable to agree whether there should be harsher penalties for selling or sypplying synthetic cannabis.
A bill by National MP Simeon Brown proposed increasing penalties in the Pschyoactive Substances Act to from two to eight years.
But in its report on the bill the Justice Select Committee said it cannot agree on whether it should and it will now go back to the House for debate in October.
The committee agreed synthetic cannabis was causing significant harm but it had also received advice that "stronger penalties does not necessarily produce a deterrent effect."
"National members argue that the bill would provide appropriate penalties for harmful substances that have yet to be listed, this process can take up to a year.
"As these psychoactive substances are easy to create or modify, National members believe there needs to be a catch-all provision imposing a penalty that is proportionate to the harm being caused," the report said.
"Labour members observe that the intent of the bill does not align with the intent of the principal Act, which is to regulate (and not prohibit) low-risk psychoactive substances. They consider a broader response is
necessary and that drug related offences should be dealt with in the Misuse of Drugs Act."
A review of the Act, which was overdue, had been carried out by the Ministry of Health and a draft report presented to the Health Minister, the report said.
Simeon Brown said his bill would offer a solution while the wider review was being carried out, and he hoped the bill would get support from New Zealand First when it went back to Parliament.
"We need to crack down on the the supply of these drugs, we don't need to wait for the government to come back from their working group, we need to act now because people continue to die."