An Actuarial View of Justice

(First published: Actuary Australia Aug 2005 — 24opinion


Our professions both claim to be rigorous in reasoning. But there is one fundamental difference. Our arguments are rooted in science while their final arbiter is opinion. Actuaries and the lawyers have many similar traits. We are both inclined to be pernickety about detail and both in some danger of not seeing the forest for the trees. We both have some difficulty communicating with the public at large.


The actuary's excuse is that we are number-smiths. A lawyer's training however is as a word-smith and I don't know their excuse. Somewhere along the way they have fallen out with the punctuation-smiths, which doesn't help. Mr Justice Owen (England, July 2000) told a jury they don't have to be certain, they just have to be sure, so rather more seriously they've fallen out with the meaning-smiths too.


Our professions both claim to be rigorous in reasoning but there is one fundamental difference. Our arguments are rooted in science while their final arbiter is opinion. Another major difference of course is that their decisions can really make a mess of an individual's life.


I have been studying court outcomes for several years now but the Schapelle Corby case gives me the excuse to air these observations now. My analysis of her case is quite brief. Was there an ability for someone else to put the drug in her luggage? Yes. Did the prosecution establish that Ms Corby put the drug in her luggage? No. Did the prosecution establish that her testimony was false? No. Has the case been proved beyond reasonable doubt? No. Case closed. Everything else seems to be mere background noise. An interpretation of demeanour might be harmless for a misdemeanour but hardly factual enough to decide between freedom and a lifetime in gaol.


The standard for proof of guilt is generally quoted as "beyond reasonable doubt". There are some famous studies of people's opinions (even a Nobel prize) showing how different phrasing of the same question readily provides contradictions. To be compatible with that other oft-quoted tenet that someone is "innocent until proven guilty", the same standard of proof should be re-worded as "no reasonable possibility of innocence", which I suggest immediately conjures up a different frame of mind and could well result in different outcomes. But that is only a small part of the problem.


Just recently (England, 25 May 2005), Paul Blackburn was acknowledged by an English court to have been wrongly convicted after spending 25 years in prison. In Britain and the USA, there have been hundreds of such cases, more still if you include people freed on initial appeal and then of course inevitably many, many more unacknowledged because evidence is not found to correct an injustice. If a child's cardigan hadn't been found in the desert, that would have been the fate of Australia's own Lindy Chamberlain.


Since one of the requirements of getting early parole from gaol is admitting guilt, the figures are no doubt even higher still. The authorities tried to cower a Michael Shirley (England, July 2003) with this medieval practice, even after DNA showed he had been wrongly convicted. He spent 16 years in gaol because three pieces of circumstantial evidence showed he could be the culprit: he was in Portsmouth on the night of the murder, he owned a pair of shoes of the same brand as the murderer and his blood type was the same as the murderer (about 30% of people have this blood type). Three could-haves amounted to a did-do in the eyes of both the jury and then the initial appeal judges.


If a judge's findings need to extend to more than a couple of pages, I suggest it is a very good clue the case hasn't truly been made. A good example is the appeal judges' findings at Sally Clark's first appeal (England, October 2000). Any actuary reading it unknowingly would think it were a satire with a whole string of trivial reasons for guilt such as on one occasion her husband was away and on the other he wasn't but he was going away the next day. Two years later Sally Clark was admitted to have been wrongfully convicted.


I'm sure all the reasons for guilt listed by those appeal judges would fail any significance tests, though statistical science isn't one of my strengths. I must have done well enough in the exams, as the London Institute asked me to be an Assistant Examiner soon after passing but they never asked me again, which shows the system works. If actuaries need to take exposure to risk into account when assessing probabilities, then surely judges do too when dealing with circumstantial evidence.


A Mr Hoogstraten had a dispute with a business colleague, Mr Raja, and paid two men to 'rough him up'. They shot Mr Raja dead. In the appeal court proceedings (England, December 2003) the judges stated, "... because there was no evidence that Hoogstraten foresaw that the two men would have deliberately turned the gun on Mr Raja, he could not be prosecuted for manslaughter. If, however, Mr Raja had been killed accidentally by Hoogstraten's two alleged henchmen, he could have been convicted of manslaughter."


I suspect most actuaries get a warm glow from that meticulous assessment if not from the story itself. My brain has a mind of its own and its favourite pastime by day and night is to hunt inconsistencies. It gave up hunting snarks long ago and, honestly, I fight hard to stop it tackling windmills. It is just fascinated by inconsistencies and there's something inconsistent about judges on one occasion behaving so meticulously as above and on others making unmeasured leaps of guesswork when convicting someone solely on circumstantial evidence.


There are lawyers engaged in fighting the miscarriage of justice. One example is but their efforts are concentrated on helping victims of the system

rather than changing the system to prevent future cases. Three things stand out as being great weaknesses in judicial systems. Firstly, judges are assessing circumstantial evidence without any idea that there is an actuarial textbook on probability theory. The second is that there is no requirement to investigate the cause of an acknowledged wrong conviction and none is ever done, in England at least. That is an amazing state of affairs and accounts for why nothing changes. It cries out for a control cycle procedure. The third is that judges don't appreciate it is a much greater fault to convict an innocent person than to acquit a guilty one.


That premise I suggest is not just an opinion. Convicting an innocent person is clearly a contradiction of what justice is all about, protecting people from the wrongdoing of others. In science such an inconsistency is a sure measure of fundamental error. Some people argue that protecting the community at large is more important than protecting an individual but there are scientific holes in that argument, since when an innocent person is convicted of a crime, the authorities stop looking for the real culprit and the public at large is not being protected.


I'm not suggesting judges aren't honourable men. They found Derek Bentley not guilty of murder (England, July 1998) 45 years after the authorities hanged him. One last squeeze of the inconsistency bottle, why are they concerned enough to correct a book entry but not the methodology that let the error happen? There is one hope on the horizon. UN and EU justices are paying much heed to individual human rights and perhaps this will gradually pervade the more antiquated judicial regimes. It is unlikely change would come from political circles since although they are numbers-men, they think the only truly universal constant is 51%.





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