Does the very improbability of an accusation mean that it is more likely to be true?

That is the argument advanced by prosecutors in the case of Cardinal George Pell, and it indicates a dangerous dynamic in trials for some cases of historic sexual abuse. Convincing evidence leads to a guilty verdict; unconvincing evidence also leads to a guilty verdict.

Cardinal George Pell’s appeal of his convictions for sexual abuse was heard last week in Melbourne, and the proceedings illustrated how sex-abuse trials are different from other sorts of criminal trials. Those anomalies had a role in the false convictions of Cardinal Pell, which I have outlined previously in these pages.

The point here is not that there are wrongful convictions. The world learned that about Australian justice decades ago in the “dingo” case, dramatized by Hollywood, where parents were falsely convicted of killing their own child. Those false convictions resulted in part from public frenzy, a frenzy in which the religious beliefs of the family — Seventh Day Adventists — played a role.

Wrongful convictions are not a uniquely Australian phenomenon; they are widespread. Americans know the case of Alaska Sen. Ted Stevens, wrongfully convicted in 2008 with the full knowledge of the most senior prosecutors in the Department of Justice. If the longest-serving Republican senator in history can be falsely prosecuted by a Republican-led Justice Department, then no citizen is safe from corruption among the police and prosecutors.

Canadians know false convictions, too. For nearly 20 years, the leading forensic pathologist for child deaths in the country, Dr. Charles Smith, provided false evidence, wrongfully convicting parents of raping and killing their own children.

Neither is the point here that police forces and prosecutors can be corrupted. The Victoria Police Department, which launched a targeted investigation against Cardinal Pell long before there were any complaints against him, is now known for having massively violated the rights of the accused. There is at the moment a judicial inquiry into the Victoria police and prosecutors, who for 20 years used defense attorneys as confidential informers, a gross violation of due process and fairness.

When it was revealed late last year, the Victoria police and prosecutors labored mightily to cover it up and prevent it from becoming public. So it is beyond dispute that the Victoria police have been for decades, at the highest levels, willing to engage in fraud and cover-up to get those they want.

The point highlighted at the appeals court hearing is different. It is that in a well-intentioned attempt to make it easier for sex-abuse victims to seek justice, the standard measures of credibility are significantly modified, such that certain weaknesses in testimony become strengths.

This is the key to the Cardinal Pell convictions, as the prosecution only provided the testimony of one alleged victim. There was no corroborating evidence presented, and the testimony of the victim was contradicted by numerous defense witnesses. The only grounds for conviction were that the jury believed the victim, against all contradictory evidence.

While wide experience shows that false accusations in sex-abuse cases against priests are rare, it does not mean that in a particular case the victim can’t be mistaken, confused, coerced or lying about the alleged abuse. Yet the standards to evaluate witness credibility are weakened in sex-abuse trials, in a well-intentioned attempt to make it easier for victims to testify.

To begin with, in Victoria, victims are allowed to testify privately, with a video of the testimony shown to the jury. This is a remarkable departure from the principle that testimony is to be offered and tested in open court.

The trial of Cardinal Pell was not an open trial; the video testimony of the victim will never be seen by the public. One of the checks on prosecutorial excess, namely that the work must be subject to public scrutiny, did not apply in the Pell case. That is standard practice in Victoria.

More profoundly, in sex-abuse cases, the very things that would undermine the credibility of testimony are adduced to be a mark in its favor.

Are there no contemporary accounts of the victim telling others about the alleged crime? That is to be expected, as victims often do not speak about the abuse until many years afterward.

Is the witness himself not trustworthy, having had a history of drug addiction, criminal behavior or fraudulent activity? All that is conceded and argued as evidence of the traumatic effects of the abuse, which set off a downward spiral in the life of a victim.

Does the testimony contradict itself or contain gaps that strain credulity? The horror of abuse means that it is to be expected that painful and wounding memories are partial or not entirely accurate.

Did other supposed victims deny that any abuse took place, as was the case regarding Cardinal Pell? Yes, but it is common for victims of sexual abuse to keep it hidden, even deny it to those close to them.

Is it simply not possible, with any degree of certainty, to establish the truth of competing claims 40 years after the fact? Certainly, but, nevertheless, the police bring decades-old sex-abuse claims.

All of this means that in historic sex-abuse cases, the compelling, coherent, consistent and corroborated testimony of an alleged victim is an argument for its credibility. At the same time, testimony that is contradictory, inconsistent and full of gaps is also an argument for its credibility. The jury is faced with the option of believing the alleged victim because he is credible or believing the alleged victim because he is not credible.

The reasons for believing a victim’s flawed testimony are not in themselves unreasonable. But they create at the same time a most difficult situation for the innocent accused.

This dynamic was evident at the appeals-court hearing. Justice Chris Maxwell characterized Cardinal Pell’s convictions as “wildly improbable.”

The prosecutor, Christopher Boyce, claimed in response that the very implausibility of the crimes was an indication of their truth. The prosecution position is that the “outlandish” nature of the accusations was itself an argument for their veracity.

“We’ve said somewhat ad nauseam if you are going to make it up … why make it up?” Boyce told the judges.

Of all places, a criminal court ought not be surprised that people say false things in court for a variety of reasons. There is even a crime for those who do so deliberately. It is called perjury.

Cardinal Pell’s case lies now with the appellate-court justices, while Cardinal Pell himself remains in solitary confinement in jail. Whether he remains there will depend on whether the justices conclude that the jury was right to believe an unbelievable story, precisely because it was that.

Father Raymond J. de Souza is the editor in chief of Convivium magazine.