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Challenges in Explaining DNA Evidence to Jurors: A Defense Attorneys Point of View The Science of DNA Profiling: A National Expert Forum Dayton, OH August.

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Presentation on theme: "Challenges in Explaining DNA Evidence to Jurors: A Defense Attorneys Point of View The Science of DNA Profiling: A National Expert Forum Dayton, OH August."— Presentation transcript:

1 Challenges in Explaining DNA Evidence to Jurors: A Defense Attorneys Point of View The Science of DNA Profiling: A National Expert Forum Dayton, OH August 14, 2005 Edward J. Ungvarsky, Special Counsel (202) , Public Defender Service for the District of Columbia

2 Introduction/Goals What do we know about what jurors think of DNA evidence Pretrial: Evaluating DNA evidence with jurors in mind Trial: Presenting DNA evidence with jurors in mind

3 What do we know about what jurors think of DNA Evidence?


5 CSI Effect Debate in Popular Media Prosecutors complaints – Not getting convictions where used to – Being held to too high a standard – false, impossible forensics – Expensive and burdensome Simon Cole analysis – TV shows may make jurors more inclined to convict because they falsely portray forensic evidence as unambiguous and certain

6 Juror Questionnaires/Experiments PDS – December 2003 – DNA is most reliable form of evidence NIJ Study – Hon. Michael Dann – Less than 1/3 successfully rejected Ps fallacy – contamination Jonathan Koehler articles – Difference between approaches Odds v. probabilities Jurors better understand odds Anecdotal – Interviews with jurors from high profile cases – DC jurors

7 Summary of Conclusions Jurors dont understand forensic DNA profiling Jurors see DNA as most reliable forensic science Jurors CAN be persuaded that DNA is not infallible (n.b.: necessity for double negative) Different statistical approaches have demonstrably different effects

8 General Myths that Need Debunking DNA is uniqueDifference between uniqueness of genome and 13-loci forensic profile Allele-calling is an objective science Allele-calling requires human interpretation Scientists are neutral and laboratories are well-run Houston, VA, FBI, Cellmark, …

9 Pretrial: Evaluating DNA Evidence with Jurors Perspectives in Mind

10 Pretrial Preparation Need to know the DNA evidence as well as the experts Once you understand what DNA evidence is and isnt, you should immediately begin to evaluate its impact on your choice of, and development of, your defense theory You need to think about ways to explain the presence of DNA in a way that jurors will understand and accept

11 Understanding DNA Evidence Meetings – National meetings Promega, AAFS, Forensic Bioinformatics Local trainings Experts – At this meeting – Others – Develop own

12 Understanding DNA Evidence Web: – – Jennifer N. Mellon, Note, Manufacturing Convictions: Why Defendants Are Entitled to the Data Underlying Forensic DNA Kits, 51 Duke L.J (2001), available for free online at Scientific Literature – Journal of Forensic Sciences – Forensic Science International – Non-Forensic Journals (Nature, Genetics, etc.)

13 NRC I and NRC II Natl Research Council, DNA Technology in Forensic Science (1992) [NRC I]: There is lots of good language and it is easy to read. Natl Research Council, The Evaluation of Forensic DNA Evidence (1996) [NRC II]: For many, it is the bible of forensic DNA. You should own a copy or have access to one.

14 John Butler John M. Butler, Forensic DNA Typing: Biology, Technology, and Genetics of STR Markers (2d ed. 2005) Dr. Butler is a scientist at NIST. His treatise is THE forensic DNA book to own and to present before a forensic scientist in court. The second edition is over 600 pages.

15 Forensic DNA Treatises Forensic DNA Evidence Interpretation (John Buckleton, Christopher M. Triggs & Simon J. Walsh eds., 2005). Scientists from outside the United States often bring a different perspective from conventional wisdom in the U.S., where the FBI and government crime laboratories are so dominant. Norah Rudin & Keith Inman, An Introduction to Forensic DNA Analysis (2d ed. 2002). A standard textbook in forensic science programs across the country.

16 Treatises: Forensic DNA Statistics David J. Balding, Weight-of-Evidence for Forensic DNA Profiles (2005). Dr. Balding is a professor of statistical genetics at Imperial College in London, England, who, among other things, has co-authored some of the leading articles on the interpretation of cold hit DNA evidence. Ian W. Evett & Bruce S. Weir, Interpreting DNA Evidence: Statistical Genetics for Forensic Scientists (1998). With good examples to help you through the math.

17 Treatises: Statistics David Freedman et al., Statistics (3d ed. 1998): This is a university textbook, with intuitive examples, written with a minimum of difficult mathematics. Michael O. Finkelstein & Bruce Levin, Statistics for Lawyers (2d ed. 2001): Like Freedman, but more targeted.

18 Discovery

19 Obtain Discovery Why you need the raw data: Analyst may have miscalled alleles To see the graphs of reagent blanks & control samples to look for contamination Allows your expert to reanalyze data or show data at different settings To show the jury at trial To check for manipulation of data by analyst Get bench notes of analyst as well

20 Review Discovery Signs of contamination in reagent blanks and positive and negative controls Masked contributors (misinterpretation of mixtures) Miscalled alleles (highly subjective art) – Artifacts – Stutter – Allelic dropout, false peaks – MAC v. P

21 Consult with Independent Expert Another set of eyes Expertise and experience Not replacement for own assessment of DNA evidence

22 Put Yourself in Jurors Shoes How is the DNA evidence significant to the charges? How does it relate to the remainder of the evidence? What is an innocent explanation for the DNA evidence? – MUST have jurors think about DNA from the perspective of the defense

23 Evaluating DNA Evidence at Trial From Defense Perspective Your client is the source of the DNA – Was involved in the offense but was legally justified: consent, self-defense – Was not involved in the offense: DNA transfer, prior contact, malfeasance, contamination Your client is not the source of the DNA – Coincidental match – False reported match or inclusion (failure to properly call alleles, etc.)

24 Transfer - Transfer: through towels, laundry basket, brushing against someone on the subway - Other reasons for clients saliva, skin cells, blood, semen, hair to be at scene (e.g., frequent visitor at decedents home)

25 Malfeasance Deliberate contamination with clients profile in testing process

26 Contamination – Can occur at collection, extraction, amplification, injection – Look at raw data for reagent blanks and positive and negative controls – Degraded or low copy # DNA increases risk – Look to see if laboratorys protocols were followed – Look at sufficiency of protocols, proficiency tests, and reviewing process – Have a theory for why clients DNA would be near sample during collection or testing

27 Contamination Contaminated Positive Control

28 Inaccurate Calling of Data Masked contributors (misinterpretation of mixtures)

29 Inaccurate Calling of Data Miscalled alleles (interpretation, not science): stutter

30 False Positives: Josiah Sutton Complainant IDd Sutton as rapist; Sutton convicted and sentenced to 25 years Rain from holes in roof of lab may have caused contamination Recent retesting exonerated Sutton Alleles found: 1.1, 2, 4, 4.1 One rapist: (2, 4) Other rapist must be: (1.1, 4.1) Sutton: (1.1, 2)

31 Coincidental Matches – There is a match, but it is coincidental – Perpetrator could be a relative (still difficult) – Perpetrator could be a non-relative (should concentrate on lowering the RMP through statistical arguments) – 6/16/89 U.S. Open – 4 pro golfers made a hole in one on the same hole, same day. P = 1 in 89 quadrillion (Harvard professor to Boston Globe)

32 Independent Testing Different expert than consulting expert who reviews prosecutions work Results of independent testing – Whether to conduct independent testing is complicated judgment call – Face possibility that exclusion may not occur – Assume jury will find out you tested Lab discloses Prosecution witness or attorney blurts out

33 During Preparation, Remember the Jurors Software printouts – what would juror think about this? Interviewing prosecution experts – what questions would a juror ask this person? Interviewing independent experts – May sound great but is it understandable – Expert both good on merits and personable Quality Control – what has lab done to stop recent problems from occurring in its lab Ability to Test – what could prosecution have tested but didnt?

34 Presentation of the DNA Evidence at Trial with Jurors Perspectives in Mind

35 DNA Trial Counsel? Different viewpoints – My viewpoint: You dont have eyewitness counsel or informant counsel, so you dont need DNA counsel. You dont have DNA jurors, dont have DNA counsel. – If DNA Counsel – Counsel should be present entire trial

36 Presentation of DNA: Voir Dire Jury Selection – What do jurors think about DNA evidence – What do jurors think about OJ Simpson case – Learn about your jurors – Educate your jurors – Open-ended questions – Questionnaires – Get commitment from jurors that they will not convict unless they UNDERSTAND the DNA evidence

37 Presentation of DNA: Opening Statement Put forward your understanding of the DNA Incorporate DNA evidence with rest of anticipated evidence Dont give away secrets Dont talk about what you dont understand Dont bore the jury

38 Cross-Examination Bias is Always Relevant – Dont put witness on pedestal, treat like any other witness – Who is your client? Determine what the LIMITED scope of C-X should be based on your defense theory and what you are planning to question – i.e., dont question credentials of prosecution witness who will admit to DNA transfer Question the SCOPE of experts expertise – Forensic scientist v. statistician

39 Practice Pointers Short, targeted cross-examination – One fact per question, building upon each other, lead – Use the jargon correctly – Dont Use Jargon – Keep it to minutes (2 days = 2 hour jury deliberation, conviction) – Preempt fallacies Now doctor, saying that RMP is 1 in 100 does NOT mean that there is 1 in 100 chance that the suspect is not the source of the DNA, right? And that false assumption is referred to in the literature as the prosecutors fallacy, right

40 Prosecution DNA Expert Do not spar! Dont try to out- expert the expert; youre an intelligent, well-informed layperson, not scientist, and jurors know that


42 Evidence of 3 rd Party PeakRFUStutter %Protocol %Protocol Recc. Analyst Call %10%Stutter Genetic profile %12%Genetic profile Stutter 28301Genetic profile

43 Evidence of 3 rd Party FBI protocols: % > 12 = genetic profile FBI analyst: technical artifact ~ 12 %

44 Do You Call Your Own Expert? Differing opinion/interpretation of DNA results Prosecution bears burden of proof Set Up battle of the experts – What will your expert say? – You must understand DNA and talk about testimony with expert before expert testifies

45 Direct Examination Direct Examination should be about as long as attention span between breaks (1.25 – 1.5 hours) – Includes qualifications Use analogies and visuals – TV, not radio, generation – Cinderella analogy Explain through questioning difference between your experts area of expertise and prosecutions, and why that matters Prepare expert for cross-examination Prepare re-direct examination – LAST WORD!

46 Closing Argument Visuals? Yes, yes, yes. PowerPoint? No, no, no. – Breaks down – Inflexible – Focus should be on the lawyer and the connection you have made with jury over course of case Simple – Do not get overly technical Demystify; bottom line, science v. art Empower jurors



49 Questions? Edward J. Ungvarsky (202) PowerPoint and Case materials nder/forensics/ nder/forensics/

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