6.3.1 Bayesian fundamentalism

An approach that might be called Bayesian fundamentalism is illustrated by the case of R v Denis Adams.^[30] This was a case of rape by an individual unknown to the victim. The victim described her attacker as ‘aged 20 to 25’. The accused, Denis Adams, had an alibi, was 37 and was not picked out by the victim in a line-up. The victim also estimated Adams’ age as ‘40 to 42’. The only evidence linking Adams to the offence was a DNA match, which a prosecution expert gave as 1 in 200 million. Crucially, the defence expert suggested that the jurors should analyse the whole case in mathematical terms (a bit like you did in the previous activity, but for every piece of evidence!), and the prosecution accepted this was valid. However, the Court of Appeal (obiter, because it was not raised in the appeal) expressed huge scepticism towards this approach.

• 1 R v Denis Adams (No 1) [1996] 2 Cr. App. R. 467.