The fatal accident inquiry into the Glasgow bin lorry crash has shed considerable light on events, but a number of questions remain unanswered.

Most notably, these include the dozens of questions the lorry's driver Harry Clarke refused to respond to, when asked about the accident which killed six people just before Christmas last year.

One query was answered when Lord Advocate Frank Mulholland defended the Crown Office against criticisms over its failure to prosecute Mr Clarke after the crash.

This decision was deeply unpopular with the grieving families of those who lost their lives. The FAI heard that Mr Clarke had concealed his history of blackouts from employers and shocking revelations about previous incidents in Mr Clarke's employment, including his having fainted while at the wheel of a bus containing passengers in 2010.

It is probably fair to say that the decision was unpopular with the public, too, as Mr Mulholland acknowledged. However he said crown officials were duty bound to take the decision they did, as there was insufficient evidence in law to bring a prosecution. The time that had elapsed since Mr Clarke's last blackout and the fact he had been cleared to drive by doctors, mean he could not be charged with dangerous driving.

The decision may have been legally legitimate, but that does not mean the law is right. The families of Mhairi Convy and Laura Stewart were not the only ones troubled by similarities between the George Square crash and the one in which the young students died, after epilepsy sufferer William Payne passed out at the wheel of a Range Rover, four years earlier.

The FAI into that fatal accident also heard that the driver had concealed his medical history and in that case too, calls for a prosecution were ruled out due to a lack of evidence. This was surely an opportunity missed for reviewing the law.

The Lord Advocate's detailed defence of the Crown's actions did not explain fully why Mr Clarke could not face a lesser charge, in relation to his failure to alert the DVLA to his medical problems, for instance. There is no evidence Mr Clarke must have known he was unfit to drive, Mr Mulholland says, which again may be legally accurate, but sits uncomfortably the FAI's revelations that the driver went to lengths not to reveal his history of blackouts to employers.

Dorothy Bain QC, representing the family of Jacqueline Morton at the FAI, accused him of telling a pack of lies in order to retain his licence. Mr Clarke's lawyer, Paul Reid QC says his client is not a liar. "He is a very ordinary man who has the failings of ordinary men," he claimed.

Some would hope for higher standards. A private prosecution may yet be possible and it it is understandable that the relatives of some of those who lost their lives wish to bring one.

We await the FAI's findings, but it has raised significant questions about how easily drivers can gain and keep a license when there are questions over their fitness to drive, and about the lack of legal response when such problems come to light. And it has left behind a strong public sense that justice has not yet been done.