Unanimous jury verdicts could be abandoned next year after the Government's introduction of legislation that overhauls the jury trial system.
The legislation does away with the long-established need for a unanimous verdict from all 12 jurors before anyone can be convicted of a crime. It says an 11-1 verdict is enough.
The bill also lets police seek a retrial for those acquitted on the most serious charges if compelling new evidence comes to light or the original trial is found to have heard tainted evidence.
But warnings from the highest level say the change to double jeopardy rules breaches the Bill of Rights.
"The proposal will result in all persons who were accused and acquitted of these charges, regardless of the seriousness of the relevant circumstances surrounding the charge, having to live with the possibility of continued police investigation, renewed prosecution and other onerous consequences of exposure to the criminal justice system," Attorney-General Margaret Wilson said.
A measure expected to provoke complaints from defence lawyers is the fast-tracking of committal hearings to speed up the time it takes to get to trial. Prosecutors will need to present evidence only in written form, and defendants will have an oral hearing only if a judge believes it necessary.
The legislation will have its first vote next week and could be passed next year.
In a report to Parliament, required under the Bill of Rights Act, Ms Wilson said the double jeopardy rule was of "great significance and importance".
"It is seen as a fundamental building block of the criminal justice process and a basic safeguard of civil liberty in our legal system.
"The fundamental purpose of the double jeopardy rule is to protect individuals against the excessive use of State power. The State, with all its resources and powers, should not be allowed to continually subject an individual to repressive and repeated prosecutions by the State."
The change to double jeopardy rules was sparked by the trial of a New Plymouth gang member who got off on a murder charge when a witness lied about vital fingerprint evidence. He could not be retried even after the witness recanted.
Ms Wilson said in cases where the courts had heard tainted evidence the accused should be retried.
But the net had been cast too wide in the case of fresh and compelling evidence possibly being used to seek a new trial in crimes involving a sentence of at least 14 years. That captured more than 40 different offences, including blackmail and aggravated burglary.