RSSeNEWS to be determined...

Nurse Benjamin Geen's defence team asserts he is a victim of a "major miscarriage of justice" as it begins an appeal to overturn his murder conviction based on a review of the statistical evidence.

In 2006, Geen was given a 30-year sentence for murdering two patients and seriously harming 15 others at Horton General Hospital in Banbury, Oxfordshire. This is the second appeal by his defence team, whose new evidence casts doubt on whether the crimes ever took place.

Medical statistician and RSS fellow Professor Jane Hutton believes that the prosecution's assertion that the pattern of illnesses in 18 patients at Horton could only be the consequence of deliberate actions by one person does not stand up to scrutiny.

Hutton, who serves on the external affairs committee of the medical section of the RSS, says the evidence given in the summing up does not support the "conclusion that any unusual pattern was not a chance event".

The defence team is also citing expert analysis of the patients' charts by Dr Mark Heath, professor of clinical anaesthesiology at New York's Columbia University. Heath says that none of the charts support the prosecution's assertion that Geen administered muscle-relaxing drugs to stop their breathing.

Geen's appeal to the Criminal Cases Review Commission started on Monday 1 March.

The citing of statistics in court hearings has often proved controversial. The RSS commented on the issues surrounding the use – and misuse – of statistics in the wake of the Sally Clark case in 2001.

In that highly-publicised case, a medical expert witness drew on published studies to obtain a figure for the frequency of sudden infant death syndrome (SIDS, or 'cot death') in families having some of the characteristics of Clark's family. He went on to square this figure to obtain a value of 1 in 73 million for the frequency of two cases of SIDS in such a family.

The RSS noted that the approach was statistically invalid. It said "The well-publicised figure of 1 in 73 million thus has no statistical basis. Its use cannot reasonably be justified as a 'ballpark' figure because the error involved is likely to be very large, and in one particular direction. The true frequency of families with two cases of SIDS may be very much less incriminating than the figure presented to the jury at trial."

The Society's press release on issues raised by the Sally Clark case concluded: "Although many scientists have some familiarity with statistical methods, statistics remains a specialised area. The Society urges the Courts to ensure that statistical evidence is presented only by appropriately qualified statistical experts, as would be the case for any other form of expert evidence."