National claimed the number of people being granted bail despite police objections has doubled in five years.
The party is blaming the "soft on crime" government, but the data it provided as proof suggests the figure has actually trended downwards in recent years.
National police spokesperson Mark Mitchell acquired the data via a written parliamentary question posed to Courts Minister Rino Tirikatene.
The numbers, taken from the High, District and Youth courts, show between October 2017 and November 2019, about 165 bail applications were approved each month despite opposition from the police.
In December 2019 the figure suddenly skyrocketed to 703. The following month it was 719, before falling to 587 in February.
Between then and February 2023, the monthly figure never drops lower than 367, and on a few occasions surpasses 500 - well above what it was in 2017/18.
"The data is the data," Mitchell told Morning Report on Monday. "I mean, we've asked the very, very clear definitive questions of the government and this is the data that they give us back and that's the data that we've got to go off."
But with the raw data came a note: "Changes were made in [the case management system] in 2019/2020 to improve the recording of opposition to bail. Caution should be taken interpreting trends before and after this period."
Mitchell rejected this.
"I think absolutely, you can make comparison," he said. "When you look at 2018 and … just over 2000 police opposition to bails were dismissed and we fast-forward to 2022 and there's been a 147 percent increase at over 5000.
"It's completely consistent with a change of government that came in and prioritised repealing the three-strikes legislation, which was our only tough piece of sentencing legislation on the books, and emptying the and reducing the prison muster by 30 percent."
The three-strikes legislation required judges to hand down the full sentence, without parole, to anyone convicted of three qualifying offences. It was repealed in 2022, with critics saying it did not reduce serious offending, disproportionately was applied to Māori and imposed sentences that breached the Bill of Rights Act.
Mitchell said a National-led government would bring it back.
"Sometimes the voice of people has to be louder than the voice of the judges."
Since the changes made to the case management data recording in 2019/20, the number of bail applications being granted despite police opposition has trended downwards.
In the first half of 2020, the average was 525 a month. In the second half of that year it fell to 473, then to 457 in the first six months of 2021, 434 in the second, then 398 in the first six months of 2022.
There was a slight uptick in the second half of last year, averaging 450 a month.
The supplied data did not say how many bail applications there were overall, nor how many were opposed by police, making it impossible to tell if the downward trend was simply the result of a falling number of applications or police oppositions.
Labour was contacted for a response to Mitchell's claims, but did not respond.
RNZ