ICCA / RSS guide: Statistics and probability for advocates

Statistics and probability for advocates: understanding the use of statistical evidence in courts and tribunals  is an introductory guide for advocates produced by the Society with the Inns of Court College of Advocacy.

This guide seeks to assist advocates with understanding, presenting and challenging expert evidence in court, and is freely available to download from the ICCA and RSS websites.
Statistical evidence and probabilistic reasoning form part of expert witnesses’ testimony in an increasingly wide range of litigation. The guide aims to identify the main traps and pitfalls advocates that are likely to meet when handling expert evidence.  

It is hoped that the guide will encourage advocates to investigate further opportunities for professional development in the understanding, interpretation and presentation of statistical and probabilistic evidence. It should also help practitioners to consult more effectively with appropriate expert witnesses in the preparation of their cases, and know how to effectively deploy and challenge expert evidence and opinion. 

Welcoming the publication of the guide on 20 October 2017, Lord Hughes of the Supreme Court said: 

“Advocates (and judges) very often encounter experts who use statistics in their reports.  An understanding of the terminology which they use is an essential baseline from which to start in following and evaluating what they say.  More importantly, statistical propositions are sometimes beguiling, and at other times counter-intuitive.  All court users will benefit from a very basic guide to the kinds of question where statistical analysis can be useful, and, as importantly, to the kinds of question where it cannot.  This guide has been prepared with these aims in mind, and by experts who have set out to explain themselves to lawyers.  It will, I hope, be a valuable companion to those who are asked to digest, to apply, and to test, expert opinion relying on statistics.”

This guide forms part of the Society’s statistics and law activities, to encourage greater understanding and use of statistics and probability in law.