On any other day, in any other month, on any other year – this hearing would be a huge international news story. The statue of King Charles II in Parliament Square in Edinburgh would be surrounded by journalists. The Court of Session’s colonnades would be sprouting cameras and camera-men, and production staff hiding from the rain.

International correspondents would be checking their makeup and adjusting their ties before cutting live to the studio to ­report the latest developments from ­inside court number one in the Court of Session. At stake in this appeal is not simply the guilt of one man – but the integrity of our criminal justice system, the reputation of Scottish justice – and the real ­possibility the wrong person was convicted of the ­murder of 270 people and spent eight years in prison for a crime he did not commit.

But this week? This week, Parliament House’s sphinxes looked down on an ­empty square. There were no cameras ­flashing, no scrambled news crews, no American accents ricocheting off the old stones, no sober courtroom shots of the advocates ­entering and leaving proceedings, no family of the convicted man, none of the bereaved, no clenched fists, no defiant statements, no drama and no fuss. The Lockerbie case has returned to the Appeal Court for the third time – but Covid-19 spares none of us.

Instead, five of the country’s most ­experienced judges assembled online to hear one of the biggest appeals in Scottish legal history. Without the dramatic courtroom visuals, the news story didn’t quite have the impact you might expect. The ­journalists and the families were ­dialing in. The advocates too. Gone were the ­traditional wigs and gowns.

This was a sort of Zoom hearing over three days, where the gravity of the ­submissions was counterpoised with the ­informality and ordinariness of the ­medium, despite the obvious efforts of everyone involved to look professional and in earnest. Like many things under Covid-19, the sense of judicial drama couldn’t be easily rekindled online, the sense of occasion difficult to conjure when you know the Lord Justice General is having trouble working his mouse, and Lord Woolman’s wireless connection was giving him gyp.

Some of the judges were flanked by old copies of the case law which has accumulated in this jurisdiction over centuries. Lord Glennie, I noticed, had some kind of 18th century painting behind him – gold frame, probably pastoral – but the wall of faces on the screen, judicial and ­serious and attentive they were, was hardly the ordinary visual picture of the country’s highest criminal court anxiously ­scrutinising one of the country’s most high-profile convictions in the longest-running appeals case this jurisdiction has ever recorded.

Before the court, the lawyers for ­Abdelbaset al-Megrahi’s family renewed their historic submission: his ­conviction was a miscarriage of justice. He was, they say, not guilty of steering the ­explosive ­device onto PanAm flight 103 in ­December 1988. He was, they say, ­wrongly convicted by the Zeist court which was manned – lest we forget – not by 15 jurors, but by three High Court judges.

But innocence isn’t a ground of appeal in Scotland. Lords Sutherland, Coulsfield and Maclean heard the evidence and ­voted to convict in January 2001, ­contrary to the expectations of many court-watchers who had sat and listened to the Crown case.

As Megrahi discovered in his first ­appeal – overturning a conviction is no small matter in an ordinary criminal case. When that conviction is a ­screamingly high profile, geopolitically significant ­decision involving the deaths of 270 ­innocent people? Well, best of luck.

There’s only one ground of appeal against conviction in Scots law. It is this: that there has been a miscarriage of ­justice. Miscarriages of justice take many different forms. Sometimes, the judge misdirects the jury on the law. Sometimes evidence was admitted which should not have been; sometimes ­evidence is ­excluded which ought to have been ­allowed. Sometimes the case turns on ­corroboration – or the lack of it. Sometimes new evidence throws a whole new complexion on the case. Sometimes police and prosecutors have been found to fiddle the evidence. Sometimes the defence is such a disaster the whole trial becomes unfair.

Here, two main submissions survived Criminal Cases Review Commission ­scrutiny, giving Megrahi’s family a third – and almost certainly final – opportunity to clear their father’s name. First, they argue, that no reasonable tribunal could have convicted Megrahi on the evidence that was heard.

Juries leave no notes explaining their reasoning, but the Zeist tribunal was a different beast. Running over 80 pages, the judges explained – step by step – the evidence they accepted and the evidence they rejected, who they found credible, and whose evidence was not.

Megrahi’s advocates contend the court’s reasoning doesn’t hold together. The ­lawyers’ attack focuses on the ­evidence of the lynchpin witness – ­Anthony ­Gauci. The Maltese shopkeeper’s evidence was the vital link in the chain connecting ­Megrahi to the debris which fell over Lockerbie in the run up to Christmas in 1989. But considerable uncertainty ­characterised Gauci’s evidence.

His eyewitness identification of ­Megrahi as the purchaser of clothes – clothes the Crown say ultimately found their way into the suitcase which ­exploded over ­Dumfriesshire – was ­uncertain, the ­timing of the purchase ­ambiguous, his ­description of the purchaser, his age, height and appearance shifting as he told the tale.

The second ground of appeal focuses on failures of disclosure. Would it have made a difference to your evaluation of the evidence, my lords, if you’d known Gauci was in the market for a reward from the Americans? Would his ­interest in ­receiving monetary credit for his ­testimony impact on your assessment of his evidence?

Did the failure to disclose this ­financial interest rob Megrahi’s defence of the ­opportunity to test how far Gauci’s ­testimony was animated by an honest ­account of what he remembered, or to what extent he may have felt incentivised to associate Megrahi with the crime? Did the failure to disclose the evidence of this interest in a reward, as Gordon Jackson QC submitted this week, relegate the cross-examination to a “softly-softly” ­approach which could test the reliability of Gauci’s eyewitness evidence, but not its credibility?

Those are the key legal arguments. Whatever the outcome, whether the ­appeal is dismissed or allowed, questions about the disaster will continue, as will the sorrow of the many families across the world whose children never came home in 1989, and of the residents of the town of Lockerbie, for whom memories of the disaster still linger.

Someone caused a plane to fall from the sky over Lockerbie at 19.03 hours on December 22, 1988. Someone planted the explosive device in the hold which ­punctured the Boeing’s fuselage and ­precipitated its terrible descent. Was Megrahi the right man, but convicted in a flawed process? Was Megrahi an ­innocent man, dragged into the case and scape-goated for the crimes of others? And if so, who are the guilty men or women? What motivated them?

Concluding the oral hearing in ­Megrahi’s third appeal against ­conviction, Lord Justice General Carloway said the Court would give judgment “as soon as it possibly can”. The court has only one duty in law: to decide whether there has been a miscarriage of justice in this case. But the five-judge bench cannot but be alive to the international significance of their decision and the reaction which will ­inevitably follow if they conclude the Zeist tribunal reached an unsafe ­conclusion.

When Abdelbaset Al Megrahi was ­released from Scottish custody on ­compassionate grounds in 2009, it caused a diplomatic incident, with angry United States senators from New York and New Jersey demanding to know why the ­Scottish Government had “freed the Lockerbie bomber” responsible for the deaths of so many US citizens.

How they might react to the Appeal Court quashing his conviction remains to be seen. As my old law professor Robert Black used to say, judges need to have the confidence – not only of their convictions – but of their acquittals too.