Statistics and the law: what’s the verdict?

Criminal cases can feature multiple pieces of dependent evidence and multiple possible explanations for this evidence. It can be challenging to disentangle the correlations between pieces of evidence and to understand how to form a logically consistent argument that accounts for this evidence in a way that is probabilistically sound. There have been high profile miscarriages of justice that have resulted from failures in probabilistic reasoning and interpretation.

In this talk I will show how chain event graphs can be used to construct possible storylines for displaying the time evolution of events and evidence in criminal cases. These chain event graphs can both be used to investigate possible arguments when drawing up a case and to make probabilistic assessments of the strength of evidence when prosecuting or defending. I will give two examples – a drugs on banknotes case and the case of the murder of Meredith Kercher. To finish the talk I will discuss the role that statistics and probabilistic reasoning can play in criminal cases and highlight where greater collaboration is needed between statisticians and those in the legal sector.

Venue: Fulton G20