Glasgow bin lorry crash driver Harry Clarke will not face a private prosecution over the tragedy which claimed six lives.
In a rare legal move, relatives of three crash victims sought permission from senior judges to bring charges against the 59-year-old.
It followed a controversial Crown Office decision not to prosecute Mr Clarke, who had blacked out behind the wheel on the day of the fatal crash almost two years ago.
Three judges at the Appeal Court in Edinburgh ruled on Friday the family could not launch a private prosecution against Mr Clarke.
The court also rejected a similar plea for a private prosecution of motorist William Payne, lodged by the families of students Mhairi Convy and Laura Stewart, who were knocked down and killed in Glasgow in 2010.
The students’ relatives voiced disappointment and said they had been “locked in a most brutal horror story” since the crash.
The lorry driven by Mr Clarke went out of control in Queen Street on December 22 2014.
Relatives of crash victims Jack and Lorraine Sweeney, 68 and 69, and their granddaughter Erin McQuade, 18, brought the prosecution attempt to court.
Stephenie Tait, 29, Jacqueline Morton, 51, and Gillian Ewing, 52, also died in the incident.
A fatal accident inquiry (FAI) heard Mr Clarke had a history of health issues but had not disclosed his medical background to his employers or the DVLA.
A sheriff found Mr Clarke “repeatedly lied in order to gain and retain jobs and licences”.
The Crown Office insisted there was insufficient evidence to raise criminal proceedings against Mr Clarke but the families of the victims disagreed and sought permission to prosecute him on charges of dangerous driving and causing death by dangerous driving.
Scotland’s second-highest judge Lady Dorrian, who heard the Bills for Criminal Letters with two other judges, ruled in both cases: “We do not consider that the Crown made an error of law.”
She added: “It is quite difficult to conceive of circumstances in which the court would pass a bill where the Lord Advocate had examined and investigated the circumstances of the case, and concluded as a matter of informed judgment that the whole tenor and weight of the evidence did not justify prosecution.”
Judges did not consider that the state of knowledge of either motorist “can reasonably be elevated to the degree necessary to be capable of establishing beyond reasonable doubt that on the day in question they drove in the face of an obvious and material danger,” she said.
The families of Ms Convy and Ms Stewart expressed their disappointment over the ruling outside court.
Cate Cairney, Laura’s aunt, said: “Since December 17 when Laura and Mhairi were brutally mown down by William Payne, we’ve all found ourselves locked in a most brutal horror story.
“As families who had to identify their daughters, seeing them as no people ever should, we trusted the process and we trusted the law, and this law has fatally let our girls down.”
Mhairi’s father Alan Convy said: “The Crown Office and Procurator Fiscal Service from the very start nearly six years ago have done everything in their power to protect an early incorrect decision of non-prosecution, to protect the process, to protect their own self-importance and, in doing so, rather than admit they got it wrong, protected William Payne and allowed their non-prosecution of him to give a huge green light to other drivers out there who have black-outs to get on the road and to kill people and walk away.
“We firmly believe that this includes people like Harry Clarke. How many more innocent daughters, parents, brothers, sisters, nieces and nephews have to die before the Crown do the right thing and send out the right message to the public?
“If this ruling is the law, then the law is wrong in our eyes. It needs changed.”
The Crown said it acknowledged the distress caused to the relatives by the decision not to prosecute the drivers.
A spokesman said: “The Crown has an obligation to take decisions of this nature professionally and dispassionately, on the basis of the evidence.
“After carefully considering all the relevant evidence, Crown Counsel concluded there was insufficient evidence in law to raise criminal proceedings.
“We note that the court does not consider that the Crown erred in its assessment of these cases.”
Ms Convy, 18, and Ms Stewart, 20, were walking in Glasgow’s North Hanover Street on December 17 2010 when a Range Rover apparently lost control, mounted the kerb and hit them.
An FAI found the crash happened after Mr Payne suffered a “vasovagal episode” and temporarily lost consciousness.
He was initially accused of causing the deaths of the students but the charges against him were later dropped.