An approach to quantifying the plausibility of the inadvertent download defence

A table of 95% confidence limits on the probabilities for randomly downloading relatively small numbers of illegal images or sensitive documents amongst a relatively large number of other images or documents has been computed. It is anticipated that these data will assist prosecution officials in arriving at a decision as to whether or not there is a reasonable likelihood of a successful criminal prosecution when the inadvertent download defence is employed in cases of possession of child pornography, terrorist material or espionage-related documents. The same data can also be used by defence counsels to assess the strength of the prosecution's case.