In October 1999, Warren Blackwell was convicted of indecent assault. He had, it had been alleged, raped a woman at knife-point on New Year’s Eve. He served more than 3 years in prison for this alleged crime. The conviction was overturned, well after his release, this month.

Mr Blackwell’s conviction was quashed because the credibility of his accuser was undermined. His initial conviction rested in large part on the testimony of his alleged victim. Once an investigation by the Criminal Cases Review Commission had damaged her reputation, her testimony was no longer deemed sufficient grounds for a safe conviction. The verdict on Blackwell was changed, belatedly, to ‘not guilty’.

The accuser, it turned out, had a history of making rape allegations. She had previously accused at least five men of rape, but never before had her claims been substantiated.

It would be dangerous to argue from the mere fact that a woman has alleged rape on a number of occasions without her alleged attackers ever being prosecuted to the conclusion that she is a serial liar. The conviction rate for rape is only 5%, and this is plausibly due to difficulties in proving guilt beyond a reasonable doubt rather than because most allegations are spurious. A woman might genuinely be raped several times without getting justice.

However, in this case there was enough to call the accuser’s credibility into question. Not only had she made an unusual number of accusations in the past, but at least one of those accusations had been conclusively disproven. She had a history of making false allegations, a track-record of lying.

This case illustrates the importance of reputation in establishing a witness’s credibility. If someone is known to have lied in the past then their credibility is reduced, particular regarding similar claims in similar situations. Once the facts about Blackwell’s accuser were revealed, the case against him was substantially weakened, and he was rightly treated as a victim of a false accusation rather than as an assailant.

Cricket Umpire Darrell Hair has been under fire for charging the Pakistan team with ball-tampering in a recent test match against England. Having examined the ball, and conferred with a colleague, he deducted five runs from Pakistan’s total as a penalty. Pakistan were, at this point, well in the lead in the match, but staged a sit-in protest in the dressing room, refusing to continue play. The match was then abandoned and awarded to England.

Since all that happened, Hair has been accused of racism, of systematically favouring the opponents of Asian nations over the years. The International Cricket Council were due to hold a disciplinary hearing to examine the ball-tampering charge, and hopefully resolve the furore surrounding Hair, when they called a press-conference. In it, ICC Chief Executive Malcolm Speed made what the press has labelled a shocking revelation: Hair had offered to retire from umpiring in return for a secret payment of $500,000. For full transparency, they published the e-mail correspondence in which Hair made the offer.

There are two interpretations of the e-mail exchange. According to the first, Hair was feeling the pressure and offered the ICC a solution that was in both their best interests and his. If he stayed, the ICC would be stuck with an Umpire who couldn’t preside over many matches due to the allegations of bias. If he stayed, he would have to continue to face down criticism from the press and from his opponents in cricket. The game would be tarnished; his career, ruined. The $500,000 would pay up his contract, which had several years left to run, and get both parties out of difficulty.

As Malcolm Speed admitted, however, there was a much more sinister reading of events. He urged the press not to accept it. According to this reading, Hair was blackmailing the ICC, using his power to contain the emerging crisis in order to extract money from them. Some even suggested that he might have deliberately created the scandal in order to get himself a pay-off.

How credible was Speed’s claim that this more sinister view of events was mistaken, that Hair had acted honourably throughout?

Speed’s reputation, on the face of it, is solid enough. As the Chief Executive of the ICC, he certainly has high status; he is in an important position of trust. This lends credibility to his claim.

His ability to see is more limited; it’s difficult for him to tell what was going on in Hair’s head. Yes, he had access to the e-mail correspondence, but he admitted in the press conference that this could be read in either of two ways. Unless he had private correspondence or conversations with Hair in addition to the published e-mails, then his access to the evidence is the same as everyone else’s, and so he is basing his interpretation of events on background knowledge rather than clear first-hand evidence.

Speed certainly suffers from a vested interest. As someone with a great deal invested in the cricket, and whose responsiblity is to protect the sport, he has a lot to lose if the reputation of cricket is damaged. This certainly weakens his sympathic interpretation of Hair’s actions.

Speed’s level of expertise is a little difficult to assess. In this context, expertise would involve knowledge of Hair. Is Hair the type of person who would try to make money out of a potential disaster? Without better knowledge of the relationship between the two, it’s impossible to tell whether Speed possesses this expertise.

Finally, there is the issue of neutrality, which is again difficult to assess. If Speed and Hair have had a long and productive professional relationship, as may well be the case, then Speed may well have a bias towards Hair, and so a reason to defend him. If, on the other hand, they have no such rapport, or even a disliking for each other, then things may be different.

To reach an overall judgement on the credibility of Speed’s claim, then, his reputation and possible expertise must be weighed against his poor ability to see, vested interest, and possible bias.

What’s your judgement?

When we think of pyramids, most us think of Egypt. According to an article in The Economist (August 12th-18th 2006 edition, page 34), historian Semir Osmanagic has suggested that we should think of Bosnia. He says that he has located three pyramids in Bosnia, over 12500 years old, one of which is significantly bigger than the Great Pyramid in Egypt. Taking the article at face value, how credible are Mr Osmanagic’s claims?

First of all, on the positive side, his ability to see isn’t bad. Having speculated that a pyramid-shaped hill in the small town Visoko might in fact be a bona-fide pyramid, he has followed up his hunch by digging. The results of the archaeological surveys include what Mr Osmanagic has identified as ancient concrete and, elsewhere, paved walkways. If he has found pyramids in Bosnia, then he’s in a decent position to know that he has, so perhaps there is something to his claims.

On the other hand, Mr Osmanagic’s expertise is more questionable. The article describes him as “a self-taught archaeologist” and “an amateur historian”. These are hardly the best of credentials for someone seeking rewrite pre-history. Those conventional historians who have come forward to reject his findings are relatively better qualified, and so more credible by this criterion.

That there are pyramids in Bosnia is not Mr Osmanagic’s only controversial view; he has a reputation for backing alternative histories. He has previously written about the survivors of the lost city of Atlantis building pyramids in South America, and has been described by more orthodox academics as “a hallucinating lunatic”.

As a witness, he’s probably not ideal. Given the nature of the claim that he’s making, more and better evidence is needed.