Logical methods to interpret evidence in the courtroom get a second hearing

How much evidential weight should be put on DNA results of blood traces in criminal cases?

Emeritus Professor Tony Vignaux
Emeritus Professor Tony Vignaux.

Victoria University of Wellington Emeritus Professor Tony Vignaux has released a second edition of the book Interpreting Evidence: Evaluating Forensic Science in the Courtroom, which aims to answer this question and many more. It is co-authored with Bernard Robertson, a former Victoria lecturer, and Professor Charles Berger from the Netherlands Forensic Institute.

The book, first published more than 20 years ago, discusses the use of logical methods and probability theory to present, evaluate and understand scientific evidence in court. It is written in plain English and draws on real life cases.  

One of the ideas discussed in the book is probability, which deals with the likelihood of something happening based on information.

“Probability may be used to interpret and evaluate the weight of evidence for and against each side of the case,” says Emeritus Professor Vignaux.

“A problem that was identified with using probability in this way is that many people don’t know what probability is, or fully grasp the concept. Lawyers and judges in the past have not known about the theories of using methods such as probability to interpret evidence and consequently may have made wrong decisions.

“We aimed to make this book accessible for prosecutors, defence lawyers and judges who are reasoning with evidence—which questions should they ask so they can understand and evaluate forensic reports and other evidence?”

The authors say support for using the methods discussed in the book has grown over the past two decades, and there was demand for an updated edition.

“The ideas we discussed in our first edition have spread widely and there are more and more arguments in favour of using these techniques, which involve both the legal and the mathematical sides. It’s been a long process getting these methods into the courts, and the techniques are only going to become more popular,” says Emeritus Professor Vignaux.

The second edition introduces new methods and has a number of new case studies, and is strengthened by the addition of co-author Professor Berger who has updated two chapters from the technical forensic science point-of-view.

“The technology in the forensic world has changed rapidly, but the logic for the interpretation of evidence is as valid as ever,” says Professor Berger.

The book is used in university courses as a valuable teaching tool and the second edition will be used in the classroom and sold in university book shops.

“We have already had a pre-order of 100 books from Leiden University in the Netherlands and we expect this edition will become essential reading for potential and practicing lawyers, prosecutors, the judiciary and forensic scientists,” says Emeritus Professor Vignaux.