National says their new sentencing policy is part of it's "tough on crime" plan.

Party leader Chris Luxon has announced new law and order policies during his key-note speaker address at the conference.

A standout policy is a plan to impose a new 40 percent limit on the amount by which a judge can reduce a sentence.

MP Chris Bishop says people can still get discounted sentences.

"The maximum discount you can get should be 40 percent. Any more than that, in our view, undermines the purpose of the sentence and undermines the public's faith in the courts."

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• NZ Herald's Claire Trevett: National are feeling optimistic this time round
• Labour says National's plan to put more people in prison will cost millions
• Harsher sentences, more focus on victims: Luxon lays down the law