A reminder of the importance of judge's discretion as the National Party pitches a crime crackdown.

It's called for a limit on the sentence reductions judges are allowed to grant, limiting it to 40%.

National would also reinstate three strikes and remove taxpayer funding for cultural reports, instead diverting funds into victim support.

Criminal Lawyer Steve Cullen told Kate Hawkesby that the law often deals with people who have had horrific childhoods.

He says that's when it's important for judges to have discretion to put them on the right path again.

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