The Prime Minister has been caught in a fiery exchange on The AM Show after refusing to comment on a Court of Appeal ruling changing how methamphetamine dealers are sentenced.

On Monday, the Court released a judgement introducing "new guidelines for judges sentencing people convicted of offences related to the importation, manufacture and supply of methamphetamine".

Poverty, addiction and mental health will now be considered as potential mitigating factors. Addiction "shown to be causative of the offending" may justify a lesser sentence of up to 30 percent. Judges are also encouraged to consider whether sentencing could be adjourned while offenders undertake rehabilitation.

Prime Minister Jacinda Ardern refused to comment on the decision on Tuesday, citing the need to ensure a separation between the Government and the courts, maintaining judicial independence.

"It is a Court of Appeal decision and I am not going to comment on something that is for the Court of Appeal," she told The AM Show.

"There is a very clear distinction between the ability of us as the Government to influence decisions made by the Court of Appeal and what we do around setting the parameters for the law itself."

However, she stressed she took a very hardline view on people who "peddle" drugs. Ardern noted her Government introduced the Misuse of Drugs Amendment Act which classified two main synthetic drugs as Class A, increasing the penalty for supplying them.

"Those who peddle misery need to face the consequences of that," she said.

Despite her reluctance, The AM Show host Ryan Bridge tried to push her on giving her opinion on the Court of Appeal decision, but Ardern wouldn't budge.

"I see methamphetamine as the epitome of misery in New Zealand... It is a horrific drug," she said.

"Those who supply and manufacture, those are the ones that we have an expectation that there is a very hard line taken against."

Bridge said that sounded like she opposed the court decision, but again Ardern refused to comment.

"Ryan, you know you cannot put me in that position. A court decision is a court decision.

"As I say, we need to be clear on manufacture and supply. There is another discussion to be had about what do you do about those who aren't manufacturing, aren't supplying, but are simply users. In those cases, yes you have seen us talking about things like rehabilitation."