The Fundamental Concept of Sham Evidence

I claim that "sham evidence" is an extremely important concept. It should be one of the most central notions of jurisprudence and, in particular, of the sub-discipline that is concerned with evidence evaluation. I am worried because this phenomenon has been neglected in the relevant literature.

What I am trying to communicate is by no means the fact that various pieces of evidence may have very different evidential power, and that it is desirable that verdicts should be grounded in strong evidence. Instead the defining characteristic of sham evidence is that it looks like strong evidence, while its objective power is very weak if not downright zero.

Sham evidence can be found in relation to many kinds of suspected crimes. One category, but by no means the only one, consists of patterns in which objective and palpable findings combine with subjective beliefs in unexpected ways. An excellent example is provided by the Swedish Catrine da Costa cutting-up trial, which started in 1984 and went into a protracted but only half-finished state in 1991. Chapter 69-86 in Scharnberg (1996) were devoted to a careful scrutiny of this case. Three excellent papers are available on Internet, published at the web site of The Swedish Foundation for Forensic Psychology by Holgerson & Hellbom, Scharnberg, and Sjöberg, respectively.

Two medical doctors were tried for having murdered Catrine, a prostitute and heroin addict. Allegedly they had cut up her body and performed a sexual desecration of the corpse. Allegedly, the 17-month-old daughter of one of the doctors was an eyewitness of these crimes.

Catrine's head was never found. But the seventh vertebra was uninjured on the torso. Three expert institutes in two countries agreed that only a very skilled surgeon would be able to separate the head from the torso between the sixth and the seventh vertebrae without injuring the seventh. Hence, the uninjured seventh vertebra seemed to constitute strong evidence that the person who had cut up the body must be found among a limited group of people.

However, one and only one of the expert institutes added that there is no indication that the separation was made at this locus. A layman could have separated the head between the fifth and sixth vertebrae, and both might have been injured. And this could be explanation why the seventh was unharmed on the torso.

This is an excellent illustration of how palpable and objective facts may combine with subjective and unarticulated beliefs.

Two high jurists, one of them a judge, have proposed that experts and expert institutions should be explicitly forbidden to provide any kind of information except what is explicitly asked for by the court. The aim of these jurists was that the doctors might have been convicted on the basis of this sham evidence, if one expert institute had not corrected the court's false beliefs.

Could anyone wish for stronger evidence of sexual abuse than the presence of spermatozoa in the vagina of a child But we saw in chapter 33 that this evidence vanished at a closer look.

The same was true of Vanessa's vaginal orifice which, according to the testimony of two doctors, was greatly enlarged.

When the psychiatrist Kåreland attributed post-traumatic stress disorder to Elvira, I shall venture no guess as to whether or not this was really or only apparently perceived as strong evidence to the judges.




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Uppdaterad: 2009-11-19

Yakida