christophe.champod@unil.ch

1. Interpretation and Evaluation of Evidence Christophe Champod School of Criminal Sciences / Forensic Science Institute Faculty of Law and Criminal Sciences / University of Lausanne, Switzerland R.A. Reiss SPSA / SPIR Annual Conference September 14-15, 2010 Acknowledgements: I. Evett, G. Jackson. S. Jones christophe.champod@unil.ch

2. State of Affair Willis SM. Forensic Science, Ethics and Criminal Justice. In: Fraser J, Williams R, editors. Handbook of Forensic Science. Cullompton, UK: Willan Publishing; 2009. p. 523-45. Very important to distinguish between investigator and evaluator role of the forensic scientist Jackson & al. The Nature of Forensic Science Opinion […]. Science and Justice. 2006;46(1):33-44. Most efforts made within the scope of ISO/SEC 17025 A rather “laissez-faire” approach

3. Formulation of evaluative opinion Association of Forensic Science Providers. Standards for the Formulation of Evaluative Forensic Science Expert Opinion. Science & Justice. 2009;49(3):161-4. This document may serve as a basis for all ENFSI laboratories. Why not adopting it at EU level across all forensic disciplines ?

4. We are progressing from a cult of opaqueness to a culture of greater transparency ...because I have attempted to place before the court all of the data that may assist the jury. Fair ‘Duty of care’ Balanced Scientific Transparent Logical « Know to doubt » Edmond Locard Getting away from the God’s syndrome

5. If we can get the logic right – then this helps us to maintain balance Forensic Expert Opinion Balance? Logic?

6. NRC p. 186: “ Publications such as Evett et al., Aitken and Taroni, and Evett provide the essential building blocks for the proper assessment and communication of forensic findings.” Somewhat recognized

7. Probability of the evidence given the prosecution case Probability of the evidence given the defence case The single most important advance in forensic science thinking is the realisation that the scientist should address the probability of the evidence The ratio of these two determines the way that the scales of justice are tilted by the scientific evidence

8. 1 2 3 Principles of evidence interpretation Probability of the forensic findings if the prosecution’s proposition (Hp) is true LR = Probability of the forensic findings if the defence’s proposition (Hd) is true Work within a framework of background information Need to consider at least two competing propositions Need to consider the probability of the observations

9. Consequences of the framework There is a need for an early identification of the issues at hand (as identified by both prosecution and defence). More use of Part 33, Rule 33(5) of the Criminal Procedure Rules (United Kingdom), initiated after the Auld report (1991). In both Reed, Reed, & Garmson and in Weller, the UK Court of Appeal recently recognized its benefits.

10. Regina V. Denis John Adams (No.2), Court of Appeal - Criminal Division, [1997] EWCA Crim 2474

11. Circumstances On the 6th of April 1991, Mrs M. is victim of an assault and raped by an unknown individual. She desribed him as a caucasian male between 20 and 25 years old. A vaginal swab is taken for further investigation. A DNA profile is obtained and kept the MFSL database (before the NDNADB) Two year later, Denis John Adams is arrested for similar facts. His DNA profile matches the profile obtained from the vaginal swabs taken from Mrs M. D.J. Adams denies any involvement in the assault.

12. Evidential value ADN Match D.J. ADAMS The match probability is 1 in 200 million

13. In this case, that value is close to 1 This is the match probability What is the probability to obtain this matching DNA profile given that D.J. Adams is truly the source of the biological fluid? Probability of the forensic findings if the prosecution’s proposition is true LR= What is the probability of getting such a profile if someone else is the source? Probability of the forensic findings if the defence’s proposition is true

14. The results are 200 million times more likely if the biologicalfluidoriginatesfrom D.J. Adams than if itoriginatesfrom un unknownunrelatedcaucasianindividual. 1 LR = 1 in 200 million Pr. Coïncidence fort. Likelihood ratio = 200 million

15. Probability of the results given the defence’s proposition (hd) is true the probability of getting such a profile if someone else is the source? Why this proposition ? Critically depends on the circumstances of the case 1 in 200 million – unrelated 1 in 220 – siblings • Be transparent in our statements and ask ourselves: • Is it sufficient to pick one option (e.g. unrelated)? • Why always taking the unrelated source as a default option? Transparent

16. Is ADAMS the source of the sperm? Il will be the duty of the court to combine this element of scientific evidence (DNA) with the rest of the probative elements in the case. Such as in this case: (1) The victim Mrs M. did not recognize ADAMS (2) ADAMS had an alibi for that day

17. UK Court of Appeal rulings in relation to DNA evidence It is the duty of the expert to deal solely with the “random match probability”. The expert should not comment on the fact or probability that the defendant had been left the stain. The combination of the scientific evidence with the other evidence at hand should be left to the judgment of the jury (common sense) without any mathematical assistance. R. v Doheny and G. Adams [1997] 1 Cr App R 369R. v D. J. Adams [1998] 1 Cr App R 377

18. R. V. Peter Weller, UK Court of Appeal, [2010] EWCA Crim 1085

19. The case Hp: Peter Weller began to stroke her body, her breasts and her legs and had then inserted his finger into her vagina. Hd: Peter Weller helped her into bed. He had checked her several times and on one occasion had had to put her into the recovery position. He had indeed had to pick up her clothes, including her knickers which she had left on the floor. He strongly denied the account of the sexual assault that she had given. Directly from R. V. Peter Weller, UK Court of Appeal, [2010] EWCA Crim 1085

20. The forensic evidence Medical evidence: the injuries were not accidental and had not been caused by infection but because something blunt had penetrated her vagina. Fingers were the likely cause of those injuries. Nail clippings: The nails were swabbed and on the right hand there was only found a DNA profile for the appellant. On the left hand a full mixed profile was obtained. The major profile was that of the appellant but there was a minor full profile of another person; there is no dispute […]that the DNA in the minor profile was that of Emma. Directly from R. V. Peter Weller, UK Court of Appeal, [2010] EWCA Crim 1085

21. Transfer The four possibilities of primary transfer were: From the appellant’s contact with the hair of Emma whilst moving her hair out of the way when she was vomiting or putting her to bed. Touching Emma when putting her into bed or holding her in the recovery position. Contact with vomit. The insertion of fingers into her vagina. Directly from R. V. Peter Weller, UK Court of Appeal, [2010] EWCA Crim 1085

22. Hierarchy of propositions Has he committed the offence? ‘Evaluator’ Did he do the activity? Is this reference sample the source of the trace material? What are the activities leading to the recovered DNA? Who is the source of the DNA? (not disputed in this case)

23. Hierarchy of propositions The added value of the forensic statement is increased when we operate higher in the hierarchy Offence Specific knowledge Added value Activity Context information Source To progress, you need more context information Moving up the hierarchy requires more data and specific knowledge

24. At the first trial It provides strong scientific support for the view that the source of the DNA was contact with the vagina. Prosecution expert The evidence is more likely to be seen given that scenario than other scenarios. […] well I have in mind what strong means in terms of the scale, and I think that’s setting it too high. Defense expert

25. The Appeal However experienced someone is, the state of the science is not such that an evaluative judgment could be expressed.

26. The outcome A court in determining whether there is a sufficiently reliable scientific basis for expert evidence to be given and a jury in evaluating evidence will be entitled to take into account the experience of experts and, if their experience is challenged, to test that. It is not a blank check ! Directly from R. V. Peter Weller, UK Court of Appeal, [2010] EWCA Crim 1085

27. R. V. Barry George, UK Court of Appeal, [2007] EWCA Crim 2722

28. Evening Standard 15th November 2007

29. At 1130 on 26 April 1999, Jill Dando, a well-known TV personality was shot dead on the doorstep of her home in London. There was a single shot to the head No firearm was found There were no witnesses Barry George was interviewed on 11 April 2000 His flat was searched and various exhibits were taken for examination A single particle of firearms discharge residue (FDR) was found in an inside pocket of his coat SEM/EDX The composition of the FDR particle was indistinguishable from FDR particles at the crime scene.

30. Hierarchy of propositions Has he committed the offence? ‘Evaluator’ Did he do the activity? Is this reference sample the source of the trace material? What are the activities leading to the recovered FDR? What it a particle of FDR? (not really disputed)

31. The judge’s summing-up for the jury [Adapted from Evett, 2009] Are you sure that this is a particle of FDR? YES NO Are you sure that the particle was not deposited as a result of “innocent” or adventitious contamination? YES …then discard this evidence altogether; it will not help you at all. In that event, you may think this removes an important part of the Crown's case. NO …. then you can take this matter into account

32. [Adapted from Evett, 2009] Summing-up: continued In relation to this question of contamination, all the experts agree that there is a possibility that contamination could have occurred innocently. As to whether the risk of that having occurred was real, theoretical or low risk, the experts vary in their individual assessments... ... you must decide whose evidence you accept and whose you do not.

33. [Adapted from Evett, 2009] Summing-up: continued The Crown say –– that the particle, together with all the other pieces of evidence, overwhelmingly supports the Crown's case. The defence say ‑‑ that it is incredible, after one year, that it can be said that this is incriminating evidence. Particles are shed rapidly, and could not survive on the coat that long.

34. Applying the framework Hp: Barry George is the person who shot Miss Dando. Hd: Barry George had nothing to do with the incident. E: one fragment of FDR was found What evidence do we expect to find if Hp is true? What evidence do we expect to find if Hd is true? Expert’s view Probability of E if Hp is true: Probability of E if Hd is true: very small very small LR = 1

35. The outcome It is clear from these extracts that the summing up that the jury were directed that the evidence of Mr Keeley and Dr Renshaw provided significant support for the prosecution’s case that the appellant had fired the gun that killed Miss Dando. The judge did not consider that their evidence on this topic was ‘neutral’. In the light of the way in which Mr Keeley now puts the matter, we have no doubt that the jury were misled upon this issue. Directly from R. V. Barry George, UK Court of Appeal, [2007] EWCA Crim 2722

36. Consequences Managing the transition from source level to activity level is too difficult to allow: Leaving it to the court – it is part of the expertise Leaving it to the expert on the D-day in court. Give precedence to written reports.

37. Future of “individualisation” ?A footwear mark exampleAll other types of “categorical” evidence (handwriting, fingerprints, toolmarks, firearms, physical fit, etc..) can be treated by analogy

38. The challenge Saks MJ, Koehler JJ. The individualisation Fallacy in Forensic Science Evidence. Vanderbilt Law Review. 2008;61:199-219. Saks MJ, Faigman DL. Failed Forensics: How Forensic Science Lost Its Way and How It Might Yet Find It. Annual Review of Law and Social Science. 2008;4(1):149-71. Cole SA. Forensics Without Uniqueness, Conclusions Without Individualization: the New Epistemology of Forensic Identification. Law Probability and Risk.2009;8(3):233-255. Kaye DH. Probability, Individualization, and Uniqueness in Forensic Science Evidence: Listening to the Academies. Brooklyn Law Review. 2010; to appear.

39. Identification process: probabilities SWGTREAD – Definite conclusion of identity : This opinion means that the particular shoe or tire made the impression to the exclusion of all other shoes or tires. Weight of the FWM evidence “Earth population paradigm” “Leap of faith” (D. Stoney) All shoes on Earth ID decision – An adventitious match is a practical impossibility LR for FW evidence ? 1/all soles 99.99…%

40. Identification process: Decision Weight of the FWM evidence • Biedermann A, Bozza S, Taroni F. Decision theoretic properties of forensic identification: Underlying logic and argumentative implications. Forensic Sci Int. 2008;177(2-3):120-32. All shoes on Earth

41. What is expert A doing? Implicitely assigns prior probability Assesses the weight of the evidence Obtains the posterior probability Makes an decision according to an implicit utility function We can argue that only 2) should be the remit of the forensic scientist and that steps 1), 3) and 4) are the duty of the court.

42. Consequences and concentrate only the evidence Once you understand the process, You will abandon the concept of individualisation

43. Conclusions Interpreting evidence requires adopting a logical and balanced framework. It requires that propositions areput forward by the parties, ideally before getting the results of the forensic examinations. Forensic scientists are more and more asked to guide in relation to alleged activities more than in relation to alleged sources. Statements will have to provide detailed guidance at activity level. There is nothing wrong in relying on experience as long as it can be logically and empirically tested. The days of conclusions of individualisations (meaning to the exclusion of all others) are counted.