How doubts over evidence drove DPP to accept bus driver's plea deal

And would disputed evidence have weakened a conviction and sentencing on lesser charges?

These appear to have been key considerations for the Office of the Director of Public Prosecutions in agreeing to allow Button to plead guilty to 10 charges of dangerous driving occasioning death instead of the manslaughter counts which had been levelled against him.

The decision to accept a plea deal with downgraded charges drew an angry response from some victims' families and some of the state's politicians.

When questioned in state parliament, Attorney-General Michael Daley said he would be asking the ODPP for a "comprehensive briefing on all aspects of this matter", and Hunter MPs Dave Layzell and Clayton Barr described the outcome as "disappointing".

Leanne Mullen, whose daughter Rebecca died in the June 2023 crash on Wine Country Drive, this week released an extraordinarily powerful condemnation of the plea deal via a statement to Parliament.

In it, she described her torment, at the crash site in the 48 hours before the victims' bodies were removed from the "cold" wreckage, in the two weeks before she was allowed to see Rebecca's body, and in the subsequent 10 months she has been "tortured" by thoughts of her daughter's death.

The plea deal, she said, was "crippling" and had ruined her "faith and trust in justice".

Ms Mullen wrote that she had given investigators the time they needed with her daughter "because I had a strong belief, a trust, that in sacrificing my rights as a mother to hold my daughter close as she left this earth the police were gathering evidence that could be used to ensure justice was done in relation to this crime".

"Sadly, it wasn't the case. My daughter and her friends weren't worth the effort of a trial," she said.

"I am the one with the life sentence of knowing that the people who could make a difference decided that they would not fight to properly honour Rebecca and her friends in the way they deserve.

"They decided to do what was easy and timely, rather than what was right."

The ODPP responded by saying it acknowledged the families' anguish and, "while the ODPP takes into account their very important views, the final decision is a legal decision made by reference to many factors, including the evidence in the particular case".

The Newcastle Herald understands the evidence uppermost in the ODPP's mind related to the speed Button was driving and his use of the prescription pain-killing opioid Tramadol.

The ODPP accepted the plea deal on the basis of an agreed statement of facts which says, among other things, that he was driving too fast and that the level of Tramadol in his blood had impaired his driving.

The case includes many other facts, of course, many of them damning for Button and traumatic for everyone involved, but the plea deal appears to have turned on the speed and drug issues.

An agreed statement of facts in these terms gave the ODPP certainty that it would secure a conviction on the dangerous driving charges and that the conviction and sentencing would be based on this evidence.

One criminal law expert told the Herald that a manslaughter conviction required a "high bar" of culpability.

Convictions of this type require proof of criminal negligence, meaning a high degree of carelessness or recklessness showing a disregard for the life and safety of others.

Professor John Anderson, an expert in sentencing and evidence at the School of Law and Justice at University of Newcastle, said manslaughter convictions required a "mental element".

"You have to intend or be reckless in relation to the unlawful act which they are basing their manslaughter charge on," he said.

"For dangerous driving causing death there is no mental element; it's a strict liability thing.

"The ODPP would look very closely at that as to how they could ensure they could prove all those things - high bar, beyond reasonable doubt.

"It's a very complex, behind-the-scenes process."

In one case in 2020, Sydney man Samuel Davidson pleaded guilty to four counts of manslaughter after he drove at more than twice the speed limit with MDMA, cocaine and a high concentration of alcohol in his system, lost control around a bend and struck seven children from behind.

The impact killed four of the children instantly, dragging some of them along a cyclone fence which bordered Oatlands Golf Club and leaving one child with significant brain injuries.

Davidson received a sentence of 28 years, with a non-parole period of 21 years, reduced on appeal to 20 years and 15 years non-parole.

We will never know whether a jury would regard Button's offending as worthy of a manslaughter finding.

It is conceivable expert testimony could have raised doubts about the speed and drugs evidence and resulted in a lesser sentence for Button.

The ODPP guidelines say plea-deal charges should "appropriately reflect the essential criminality of the criminal conduct capable of being proven beyond a reasonable doubt and provide an adequate basis for sentencing".

Mr Layzell complained to Parliament on Wednesday that the lesser dangerous driving offences carried a maximum penalty of 10 years and Button could be out "in a few years" after receiving a 25 per cent discount for the guilty pleas.

In the Davidson case, which also involved guilty pleas, the judge arrived at an aggregate sentence well beyond the maximum for each offence.

So did the appeal court judges.

As reported in the Herald on Friday, the Mullens are distraught about the plea deal and that they were not given more time to digest the agreement and the agreed statement of facts in the case before Button appeared in court last week.

Victim Nick Dinakis, who was injured in the crash and whose girlfriend, Darcy Bulman, died, told the media after the plea deal was announced last week that he was "extremely pleased" with the ODPP and the outcome.

"I understand this isn't a situation that can appease everyone, but it allows myself and the other victims to try and move forward with life," Dinakis said.

For the Mullens, the plea deal has "torn apart any progress we have made recovering from this nightmare we find ourselves in".

The survivor victims of this crime are entitled to their positions on the rightness or wrongness of the plea deal.

Those accepting the outcome and those demanding a trial are both being reasonable, not that it is up to the rest of us to judge.