The suggestion comes amid mounting anger that the killer or killers of twin babies Chris and Cru Kahui may never be brought to justice.
The early days of the police investigation were hampered when the family of the twins refused to talk to investigators.
After their father Chris Kahui was found not guilty this week, police said no-one else would face charges related to the brutal killings.
Napier Labour MP and former criminal defence lawyer Russell Fairbrother yesterday called for a review of the right to silence of criminal suspects or those charged with a criminal offence.
He did not know whether Mr Kahui was "truly innocent", or had received the benefit of the doubt in a case rife with uncertainties.
"But I do know that someone in that house truly knows what happened. It cannot be right that a guilty person is avoiding criminal sanction for this most heinous of crimes."
Mr Fairbrother said he would discuss the matter with the Minister of Justice, Annette King, with a view to introducing a private member's Bill.
Former Prime Minister and Law Commission president Sir Geoffrey said talking about the law, and possible changes to it, was worthwhile - although any changes would take time. Sir Geoffrey said changes to the law had been considered "from time to time".
However, the right to silence was deeply embedded in New Zealand law - and had been for a very long time, he said.
"Changing it is a very big operation. There are arguments on both sides - no question."
New Zealand's human rights-centred law had led to many rights being developed "which did not exist less than a century ago", he said.
But Law Society spokesman and Criminal Law Committee convener Jonathan Krebs said changing the "cornerstone" law was an unnecessary reaction to what had been a very difficult case.
It was a known trend that changing common law in response to a hard case often resulted in bad law, he said. "I don't think it's a topic that needs discussion."
Auckland University associate professor of law Scott Optican said calling for a review was "ridiculous".
While police could not force people to speak pre-trial, they could call them as witnesses in a trial. Failure to speak in court is contempt, he said.
"If the police want your co-operation, they have to secure it voluntarily, otherwise you're open to coercive methods. If you think about any country . . . who operates with coercive methods to get people to speak, it's not a country you want to live in."
Ms King's spokesman said the Justice Minister would make no public comments on Mr Fairbrother's proposals. - The New Zealand Herald
