National says the Justice Minister is dreaming if he thinks more putting more police on the beat will reduce the number of prisoners.
Andrew Little says if the force is properly funded, they can better deter and prevent crime - leading to fewer prisoners.
But National justice spokesperson Amy Adams says the evidence proves the opposite will happen.
"It's not just coming from the Ministry of Justice, Police and Corrections who are saying that - it's also other specialist groups who work in this area who say it will lead to a higher prison population - and actually, you'd want it to.
"The point of having more police is for people to be safer, and have more criminals arrested and dealt with."
Ms Adams says the Government's proposed changes to the justice system will make New Zealand less safe.
"[Mr Little's] effectively calling on justices to be softer… I find that deeply worrying and quite disturbing."
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Mr Little has also expressed concern about a lack of consistency in the sentences handed down by judges.
"Getting some consistency and some guidelines would be very helpful," he told The Nation on Saturday.
Ms Adams says he needs to butt out.
"[He's] trying to control how the judiciary exercise their discretion in applying our laws."