Presentation to Juries

[Dick Dastardly]

In following the debate about McKie, I have developed a somewhat unhealthy interest in the wider issues about fingerprints and how evidence is presented.

My interest is in how the complexities of fingerprint analysis are presented to members of a jury in the US and the rest of the world.

I know that the SCRO tactic was to present a "charting enlargement" - an example of which is seen on the various sites.

I also know that Pat presented acetate overlays to the jury, which (judging from the result) was understood by the jury.

I have also seen examples on this site of powerpoint/photoshop presentations. If I may say so, the last of these looks very complex and difficult to understand to a non expert. No doubt it was carefully explained to the jury as it unfolded.

My question is this: has anyone actually carried out research to see what the most effective method is to get the points home to a jury? I know that the US permits the interviewing of jurors after a case. This is not permitted in the UK. In fact, jurors are not even allowed to discuss their deliberations outside the jury room. But there is surely some feedback about the clearest way of detailing a challenge? What methods are favoured by various experts? And can any of these methods be used for other forensic presentations such as dna, marks on gun casings etc.?

[Dr. Dror]

Dave Charlton and I are conducting research on these very issues; we have just finished collecting data and analysing two specific studies:

Study 1. We manipulated what the examiner was wearing in a mock jury study (dressed up smart, i.e., suit; vs. 'scruffy', i.e., t-shirt, unshaven), while the actual presentation content was identical. Then we examined if/how this affected if the jury found the suspect guilty or not, and if guilty, how long he was sentenced for.

Study 2. We manipulated the content of the actual presentation (same clothes this time...); here the data was presented as either 'definite match' (or not), and in the other conditions the match was presented in different formats (statistical likelihood ratios, odds, probability, etc.). In this study we also examined how potential juries conceptualize and understand different data (e.g., '1 out of a million' vs '1 out of 10 million'; or 95% vs. 99%). Again, then we examined if/how this affected if the jury found the suspect guilty or not, and if guilty, how long he was sentenced for.

We are in the process of writing up these studies (and a few others too). If you are interested, I post them on my website as they become available (at: http://www.ecs.soton.ac.uk/~id/biometrics.html).


Itiel

[Dr. Dror]

Correct www address is:
http://www.ecs.soton.ac.uk/~id/biometrics.html