Why this book?

High quality resources can already be found on this topic, which have been authored by the founders of systematic approaches to forensic evidence evaluation and which have been endorsed by national-level organisations. These include Aitken, Roberts, and Jackson (2010), Puch-Solis et al. (2012), Roberts and Aitken (2014), Jackson, Aitken, and Roberts (2015), Champod et al. (2016), Inns of Court and Royal Statistical Society (2017), and Nic Daéid et al. (2020). This resource aims to complement and extend the existing texts in the following ways:

  1. by providing more examples for each of the core concepts so that learners can see the theory in action

  2. by providing worked exercises and solutions for learners to test and reinforce their understanding

  3. by providing interactive material (in the online version of this resource) to enhance the learning experience

  4. by being based online to allow feedback to be easily given and regularly implemented, and for content updates to be easily made as scientific thinking develops and current practices change - see the sections below on how to contribute.

This book follows the main content from the Royal Statistical Society’s Fundamentals of Probability and Statistical Evidence in Criminal Proceedings book (Aitken, Roberts, and Jackson 2010) and then portions of The Logic of Forensic Proof (Roberts and Aitken 2014). We have also provided motivation for the use of probability and statistics by drawing from the uncertainty communication literature, and in particular adapting the advocated model from Bles et al. (2019) to forensic science. Put together, this resource provides an intermediate overview of why and how we use probability and the likelihood ratio for evaluating forensic evidence, including examples and exercises to reinforce understanding.

The interactive examples in the online version of this book can be found as part of an interactive application. This is to provide a standalone resource for those who are not using the book e.g. a wider audience, and also so that those who prefer to use a printed version of this book can still have fast access to the examples they need.

The content presented here is not a comprehensive guide to the evaluation of all forensic evidence. For example in the UK (as of writing this in August 2020), the numerical evaluation of impression evidence (such as fingerprints) is not widely practised compared to say, how it is done in other jurisdictions such as The Netherlands. In addition, each evidence type is currently at a different stage of scientific understanding. As a result, the exact statistical considerations for each evidence type differ, even if the general evaluation methodology is similar. More information on the state of each type of evidence can be found in the judicial Primers series commissioned by the Royal Society and the Royal Society of Edinburgh (Nic Daéid et al. 2017, 2020; Black et al. 2017).

References

Aitken, Colin, Paul Roberts, and Graham Jackson. 2010. Fundamentals of Probability and Statistical Evidence in Criminal Proceedings: Guidance for Judges, Lawyers, Forensic Scientists and Expert Witnesses. Royal Statistical Society. https://nottingham-repository.worktribe.com/output/1011545.
Black, Sue, Mark Wall, Rami Abboud, Richard Baker, and Julie Stebbins. 2017. Forensic Gait Analysis: A Primer for Courts. The Royal Society; Royal Society of Edinburgh. https://eprints.lancs.ac.uk/id/eprint/132584/1/royal_society_forensic_gait_analysis_primer_for_courts.pdf.
Bles, Anne Marthe van der, Sander van der Linden, Alexandra LJ Freeman, James Mitchell, Ana B Galvao, Lisa Zaval, and David J Spiegelhalter. 2019. “Communicating Uncertainty about Facts, Numbers and Science.” Royal Society Open Science 6 (5): 181870. https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.181870.
Champod, Christophe, Alex Biedermann, Joëlle Vuille, Sheila Willis, and Jan De Kinder. 2016. “ENFSI Guideline for Evaluative Reporting in Forensic Science: A Primer for Legal Practitioners.” Criminal Law and Justice Weekly 180 (10): 189–93. https://serval.unil.ch/resource/serval:BIB_842A724DBA9E.P001/REF.pdf.
Inns of Court, The Council of the, and the Royal Statistical Society. 2017. Statistics and Probability for Advocates: Understanding the Use of Statistical Evidence in Courts and Tribunals. The Council of the Inns of Court; the Royal Statistical Society. https://www.icca.ac.uk/wp-content/uploads/2019/11/RSS-Guide-to-Statistics-and-Probability-for-Advocates.pdf.
Jackson, Graham, Colin Aitken, and Paul Roberts. 2015. Case Assessment and Interpretation of Expert Evidence: Guidance for Judges, Lawyers, Forensic Scientists and Expert Witnesses. Royal Statistical Society. http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.723.2831&rep=rep1&type=pdf.
Nic Daéid, Niamh, Alex Biedermann, Christophe Champod, Jane Hutton, Graham Jackson, Tereza Neocleous, David Spiegelhalter, Sheila Willis, David Kitchin, and Amy Wilson. 2020. The Use of Statistics in Legal Proceedings: A Primer for the Courts. The Royal Society; Royal Society of Edinburgh. https://discovery.dundee.ac.uk/ws/files/55890125/science_and_law_statistics_primer.pdf.
Nic Daéid, Niamh, Anne Rafferty, John Butler, James Chalmers, Gilean McVean, and Gillian Tully. 2017. Forensic DNA Analysis: A Primer for Courts. The Royal Society; Royal Society of Edinburgh. https://discovery.dundee.ac.uk/ws/files/19470629/royal_society_forensic_dna_analysis_primer_for_courts.pdf.
Puch-Solis, Roberto, Paul Roberts, Susan Pope, and Colin Aitken. 2012. Assessing the Probative Value of DNA Evidence: Guidance for Judges, Lawyers, Forensic Scientists and Expert Witnesses. Royal Statistical Society. https://nottingham-repository.worktribe.com/output/1007847.
Roberts, Paul, and Colin Aitken. 2014. The Logic of Forensic Proof: Inferential Reasoning in Criminal Evidence and Forensic Science: Guidance for Judges, Lawyers, Forensic Scientists and Expert Witnesses. Royal Statistical Society. https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.733.2471&rep=rep1&type=pdf.