Two victim's families are a step closer to prosecuting police and the Corrections Department over the killings of their loved ones, in a case that would be a legal first.
The High Court at Wellington has thrown the case a lifeline after a district court judge ruled an application to file it came too late.
The application has been made to bring a private prosecution against the government departments under the Health and Safety in Employment Act for allowing murderer Graeme Burton to go free, resulting in the fatal shooting of Karl Kuchenbecker in 2007.
Jointly, Nelson woman Judith Ashton is looking to charge them over the death of her daughter, Debbie, after she was killed the previous year by convict Jonathan Barclay.
Barclay - who had a host of previous convictions - pleaded guilty to the manslaughter of Ashton by crashing into her car while driving drunk and while he was in the police witness protection programme.
The case hinges on the principle that under the Act, employers must ensure employees "take all practicable steps" to prevent harm to others.
Lawyers for the families argue that by allowing the "systemic failures" that saw these men walk free, police and Corrections bosses breached that law. They claim that had they done their duty, Kuchenbecker and Ashton would still be alive.
In the latest decision, Justice Forrest Miller said the district court had miscalculated the available time for the application and it should proceed.
He sent the case back to Wellington District Court and awarded costs to Ashton and the Sensible Sentencing Trust's Garth McVicar, who is acting for Kuchenbecker's family.
If convicted the departments face fines of up to $250,000.
One of the lawyers acting for the victims' families, Nikki Pender, said there was a long way to go. Their case was "not that different" from the groundbreaking one in which the Department of Labour successfully prosecuted the Sir Edmund Hillary Outdoor Pursuits Centre over the canyoning deaths of six Elim Christian College students in 2008.
The department laid two charges against the centre after it was found managers failed to heed weather warnings and the instructor was not fully trained.
But the Department of Labour has refused to take action over the Kuchenbecker and Ashton cases.
Judge Miller said the department accepted the Act technically applied to paroled prisoners but believed "other legislation and agencies were more directly involved".
Police and Corrections deny the Act applies.
In 2008 the Independent Police Conduct Authority slammed the inter-agency relationship between Police and Corrections which resulted in them losing track of paroled murderer Burton.
Warrants were out for his arrest when he went on a shooting spree in Lower Hutt, killing Kuchenbecker and wounding two mountain bikers. It ended only when police shot Burton in the leg.
A mix-up meant Barclay escaped jail for a driving offence and a month later caused the crash that killed Ashton. His history, including a final warning for driving offences, was recorded under his real name and the subsequent fine was entered under his new name, given as a witness in the protection programme. Had the judge known he was not a first-time offender, he would likely have been imprisoned.
McVicar said the High Court win was "a small step" with potentially huge significance and stressed he had nothing against police.