Further action is not warranted on a petition which requests a ban on plea bargaining negotiations initiated by Crown Prosecutors, Parliament's Justice Committee says.

The committee has released its report on a petition by Garth McVicar on behalf of the Sensible Sentencing Trust.

The petition requested: "That the House note that 1500 people have signed a petition requesting the Government to introduce a system under which a High Court Judge must approve any arrangement under which an originally laid charge alleging murder is replaced by a lesser charge, with the Judge empowered to order that a trial of the defendant on the original charge proceed; and, as a matter of urgency, make whatever law changes may be necessary to outlaw the practice of plea bargaining negotiations initiated by Crown Prosecutors."

The petition arose out of the death of three-year-old Moko Rangitoheriri in August 2016. His two caregivers were initially charged with murder, but the Crown later accepted guilty pleas for manslaughter. They were each sentenced to 17 years in prison, with a minimum non-parole period of nine years.

The committee sought written comment from the Crown Law Office and the Attorney-General. It says both disagreed with the petitioner on the request for creation of the judicial power to examine and possibly reject plea arrangements.

"Extraordinary intervention"

Both said this would be an "extraordinary intervention in the exercise of prosecutorial discretion".

"Crown prosecutions are conducted by Crown solicitors, on behalf of the Solicitor-General. The Solicitor-General makes the final decision regarding plea arrangements in murder cases to acknowledge that they are of significant public interest," the committee says.

"Further, the Prosecution Guidelines require prosecutors to inform the victim of any plea discussions where practical and appropriate, and give them sufficient opportunity to make their position known."

The committee says that until 2013, only the defence could initiate plea discussions. However, this meant that cases were not being resolved as efficiently as they could be, with plea discussions often taking place shortly before trial.

It says Crown Law told it that it was "desirable and appropriate" for the prosecutor to initiate plea discussions. This is particularly the case where the evidence changes in the lead-up to the trial or where the likelihood of conviction is finely balanced and the prosecutor's view of that likelihood changes during the case.

"Most plea discussions are still initiated by the defence, usually to discuss the possibility of an offer to plead to manslaughter."

Substitution of manslaughter

Both Crown Law and the Attorney-General disagreed with the petitioner's concerns about the substitution of manslaughter for murder charges.

"Both submissions noted that the guilty plea for the manslaughter charge allowed the prosecutor and the defence to agree on the statement of facts. This agreed statement of facts became public, and is what the petitioner bases his arguments on. They noted that, if the original murder charge had proceeded, the prosecutor would have needed to prove the alleged facts and, based on the evidence available at trial, may not have succeeded. The Attorney-General also noted that the manslaughter charge allowed the prosecutor to argue for a sentence that reflected the nature of the crimes committed."