Kiwis would support criminalising not speaking up in child abuse cases - Simon Bridges

National Party leader Simon Bridges believes most New Zealanders would support criminalising not speaking up in child abuse cases.

Police continue to investigate critical injuries sustained by a four-year-old in Flaxmere late in January. Detective Inspector Mike Foster says they were among the worst injuries he has seen in his 30 years of policing, but there has been a lack of information about how they came about.

On Monday, Children's Commissioner Andrew Becroft said the right to silence should be abolished in child abuse cases. Currently, the law allows people the right to remain silent and not incriminate themselves or have their words used as evidence in court.

Justice Minister Andrew Little has ruled out changing the law, saying he "could not conceive of such a power to compel someone to make a statement ever being acceptable to New Zealanders".

Bridges thinks differently, however, and announced on Tuesday that if he gains power on September 19, his Government would make the non-disclosure of information relating to child abuse an offence.

"A four-year-old has been beaten over a period of days, the worst a copper has seen in his 30-year career, and we need to make sure we are doing better justice in these sort of cases," he told The AM Show on Wednesday.

"I think we can say pretty likely there are people who will know, that won't speak up… Criminalising that, I think is something most, maybe not all, but most New Zealanders would go along with."

The National Party leader said that there would be caveats within the law to ensure the safety of people. 

"There will be a reasonable excuse test and a reasonable knowledge test if you like. Effectively, if you have seen bruising, if you were there in fact, if the child has told you, you should be coming forward in those cases," he said.

"If you are fearful for your safety and there is a reasonable, objective basis on which you can do that, you will have a good defence."

The ACT Party is also onboard with a law change. Earlier this week, leader David Seymour said if he is re-elected later this year, he would introduce a Bill into the Member's Ballot that would make failing to cooperate with police investigating a child abuse case an offence. 

"Parents and families should not be able to form a cone of silence, refuse to answer questions, and protect child abusers. That situation must end. Police must be given proper tools to investigate child abuse. Our children deserve better," Seymour said.

Little has asked for advice on whether people should be warned upon arrest that staying silent may harm their defence in court. This, however, would still require a change to the Bill of Rights, which he described as "hugely significant". 

Lawyer Marie Dyhrberg agrees that abolishing the right could have negative consequences

"It's very dangerous to have a knee-jerk reaction and to perhaps try and isolate certain cases whereby you are going to take away rights such as the right to silence," Dyhrberg told Newshub.

She said in many cases family members genuinely don't know what has led to injuries. 

"The person who often ends up being responsible for these sorts of injuries on little children, they don't do it in front of people," she said.

"You are going to run the very real risk that there will be people wrongfully convicted. There will be people under pressure who will admit to things just to take the pressure off the rest of the family." 

Failing to speak out does not always mean an admission of guilt, Dyhrberg said. There can be many reasons why people refuse to talk.

"People misunderstand questions, they're under stress, they are afraid of what's going to happen to them - all sorts of reasons."