"We have an adversarial court system, " Tommy Sheridan observed in defending himself at his perjury trial.
"In every city, every court, every day, two sides are arguing over serious crimes, like murder, rape and assault … There are two sides to every story and one loses. Why do we not have perjury trials every day?" It's a fair question.
Of course, that two sides are in stark conflict does not mean that anyone is lying.
Memories are finite, thinking is wishful. Court cases often turn on chronology - HMA v Sheridan did.
Are even the most important dates in our lives genuinely remembered, or imperfectly deduced from other memories? What we are told? What's on our birth certificates? Stressed people, in particular, make innocent errors. Court witnesses, stuck on display, cross examined and threatened with perjury, are normally stressed.
A person with perfect recall of detailed events years after they happen belongs in a circus, not a court, a distinction litigators try to preserve even in defamation trials.
That is one reason why perjury cases are hard to win. The crime of perjury, as Lord Bracadale told the jury, requires the Crown to prove beyond reasonable doubt that the accused has "wilfully given false evidence under oath or affirmation in judicial proceedings".
It's unclear quite how rare perjury trials - trials in which the principal charge against the accused is perjury - actually are.
Confident statements about the Sheridan trial's uniqueness have been flying.
It has been said to be the longest Scottish perjury trial, the most expensive Scottish perjury trial, the only Scottish perjury trial to arise out of a civil action.
This last isn't so - in 1999, in HMA v Jackson, seven police officers were tried and acquitted of perjury arising out of the late Gerard Rae's civil action against the Chief Constable of Strathclyde in 1997.
The others may be true, but the Scottish justice wagon has been rolling a long time and many trials are neither reported nor appealed.
If reliable statistics are available at all, they are likely to be buried deep.
Claims of this sort are, one suspects, based on what living journalists and lawyers can recall, using their own imperfect memories and individual experiences.
For UK journalists in 2010, "perjury trial" probably evokes a collage of politicians with their wives beside them, winning defamation actions, then going to jail.
The tradition of the libel writ with the prison lit sequel goes all the way back to Oscar Wilde.
The modern Scot perhaps thinks of police officers, as in the Jackson case itself or, later, the unsuccessful prosecution of former policewoman Shirley McKie over the fingerprint controversy.
There is a distinctive argument to be made about the importance of establishing that members of parliament or the police have not lied on oath, but the Scottish cases produce a more varied pattern.
In HMA v Cairns, for instance, in 1967, a man had been acquitted on a verdict of not proven after denying on oath that he had stabbed a fellow prisoner.
He then tried to interest a newspaper in how he had got away with murder. The appeal court held that he could be tried for perjury, though he died before the second trial.
Two of the witnesses in the original "Ice Cream Wars" trial, Joseph Granger and Alexander Reynolds, were convicted of perjury in 1985.
Not all cases are so melodramatic. In Singh v HMA in 2004, Harpal Singh was found to have lied in his evidence to a Fatal Accident Inquiry that there was a smoke detector in the hall of his basement flat.
People do lie: out of fear, out of spite, out of loyalty, out of self-interest, in and out of court, and, sometimes, for no obvious reason at all.
And whilst there may be less meticulous record-keeping for the history of perjury trials in Scotland than there is for bad weather, one would not need much experience of court work to hold these truths to be self-evident:
- There are more perjurers than there are perjury trials.
- The Sheridan perjury case has been long and costly by the standard of the average Scottish criminal trial.
There is no way for a legal system to factor in the costs of a trial in terms of the health, emotions or reputations of the key witnesses for both sides, nor any very easy way to assess its economic impact on the professional participants and the jurors.
It does not take, though, a great deal of sophistication to imagine the depth of Mrs Sheridan's ordeal before the charges against her were dropped in this case.
Her husband attacked the prosecution of them both as a waste of public money, and so, on different grounds, did his former best man turned Crown witness, George McNeilage.
The original impetus for a perjury investigation into the Sheridan defamation case came not from the parties, the Crown or the police, but the defamation trial judge, Lord Turnbull. He made pointed references to the disparity in evidence between witnesses.
At the time, 2006, both Mr Sheridan and several of his detractors held political office. By the time the perjury trial started, that was no longer true of any of the defamation witnesses.
The Crown's task is to prosecute in the public interest.
In Scotland, except in the rarest circumstances, there is no private prosecution. Decisions on prosecution are ultimately the responsibility of the Lord Advocate.
Any individual who is prosecuted has a perfect right to object, as a private citizen, on the grounds that the prosecution is ill-motivated or unjust, but only the public has the right to be satisfied that a prosecutorial decision is in its interest.
The public is both, crudely, the paying party, and, more importantly, the party affected by the shaping and administration of the law. But the public is unlikely to take a unitary view, especially of a case as complex as HMA v Sheridan.
The Crown is more often criticised for its handling of a case or its treatment of witnesses than for bringing a prosecution in the first place.
Partly, no doubt, that is because the decisions of individual fiscals are based on an intersubjective understanding of the criteria of public interest, but partly it may reflect the reporting biases of the media.
The manner in which murder, rape or assault trials are run is the subject of intense media scrutiny, but no one is likely to suggest that they are too expensive or difficult or atypical to justify investigation.
The consideration of the public interest in investigating perjury involves a more open textured discretion than that.
'Life at stake'
Yet perjury is a serious crime.
Mr Sheridan's closing statement to the jury included the words, "My life is at stake." That is scarcely an exaggeration. His liberty and his child's own right to live with him were in the hands of a jury who were properly directed to make up their minds purely on the evidence.
That evidence consisted principally of what the witnesses said on oath. It matters that people should tell the truth in court, because courts change lives.
If there is never a perjury trial, the administration of the oath becomes a ritual: perhaps anachronistic to the agnostic, who can choose to affirm; perhaps offensive to the believer, who may not wish to drag Almighty God into a secular dispute between a politician and a tabloid; ritual, either way.
Maybe it would be in the public interest to have more perjury trials. But that would not, of course, answer the question of whether it was in the public interest to run HMA v Sheridan for three months and at six figures. Was it? Only the public can decide.