Presentation on theme: "The Science of DNA Profiling: A National Expert Forum"— Presentation transcript:
1 Challenges in Explaining DNA Evidence to Jurors: A Defense Attorney’s Point of View The Science of DNA Profiling: A National Expert ForumDayton, OH August 14, 2005Edward J. Ungvarsky, Special Counsel(202) ,Public Defender Service for the District of Columbia
2 Introduction/GoalsWhat do we know about what jurors think of DNA evidencePretrial: Evaluating DNA evidence with jurors in mindTrial: 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 Prosecutor’s complaintsNot getting convictions where used toBeing held to too high a standardfalse, impossible forensicsExpensive and burdensomeSimon Cole analysisTV shows may make jurors more inclined to convict because they falsely portray forensic evidence as unambiguous and certain
6 Juror Questionnaires/Experiments PDS – December 2003DNA is most reliable form of evidenceNIJ Study – Hon. Michael DannLess than 1/3 successfully rejected P’s fallacycontaminationJonathan Koehler articlesDifference between approachesOdds v. probabilitiesJurors better understand oddsAnecdotalInterviews with jurors from high profile casesDC jurors1000 jury eligible residents of WDCHowe persuasive 9/10, 9Fingerprint 8.3, 8.6Eyewitness: 6.8, 6.6Videotaped Confession 7.6, 7.7Do you think DNA evidence can be wrong? 54%How often mistakes made DNA evidence in trial? Almost never 78%
7 Summary of Conclusions Jurors don’t understand forensic DNA profilingJurors see DNA as most reliable forensic scienceJurors 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 profileAllele-calling is an objective scienceAllele-calling requires human interpretationScientists are neutral and laboratories are well-runHouston, VA, FBI, Cellmark, …
9 Pretrial: Evaluating DNA Evidence with Jurors’ Perspectives in Mind
10 Pretrial PreparationNeed to know the DNA evidence as well as the expertsOnce you understand what DNA evidence is and isn’t, you should immediately begin to evaluate its impact on your choice of, and development of, your defense theoryYou need to think about ways to explain the presence of DNA in a way that jurors will understand and accept
11 Understanding DNA Evidence MeetingsNational meetingsPromega, AAFS, Forensic BioinformaticsLocal trainingsExpertsAt this meetingOthersDevelop 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 atScientific LiteratureJournal of Forensic SciencesForensic Science InternationalNon-Forensic Journals (Nature, Genetics, etc.)
13 NRC I and NRC IINat’l Research Council, DNA Technology in Forensic Science (1992) [“NRC I”]: There is lots of good language and it is easy to read.Nat’l 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 ButlerJohn 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.
19 Obtain Discovery Why you need the raw data: Analyst may have miscalled allelesTo see the graphs of reagent blanks & control samples to look for contaminationAllows your expert to reanalyze data or show data at different settingsTo show the jury at trialTo check for manipulation of data by analystGet bench notes of analyst as well
20 Review DiscoverySigns of contamination in reagent blanks and positive and negative controlsMasked contributors (misinterpretation of mixtures)Miscalled alleles (highly subjective “art”)“Artifacts”“Stutter”“Allelic dropout,” false peaksMAC v. P
21 Consult with Independent Expert Another set of eyesExpertise and experienceNot 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 DNAWas involved in the offense but was legally justified: consent, self-defenseWas not involved in the offense: DNA transfer, prior contact, malfeasance, contaminationYour client is not the source of the DNACoincidental matchFalse reported “match” or inclusion (failure to properly call alleles, etc.)Not going to focus on admissibility because in NM, mostly go to weight and not admissibility. However, if lab protocols are not up to snuff, should attack the methods as inherently unreliable (Patricia Charache)
24 TransferTransfer: through towels, laundry basket, brushing against someone on the subwayOther reasons for client’s saliva, skin cells, blood, semen, hair to be at scene (e.g., frequent visitor at decedent’s home)
25 Deliberate contamination with client’s profile in testing process MalfeasanceDeliberate contamination with client’s profile in testing processDon’t mean to be flippant; bias is rampant
26 ContaminationCan occur at collection, extraction, amplification, injectionLook at raw data for reagent blanks and positive and negative controlsDegraded or low copy # DNA increases riskLook to see if laboratory’s protocols were followedLook at sufficiency of protocols, proficiency tests, and reviewing processHave a theory for why client’s DNA would be near sample during collection or testingUsing different lanes?Less than 1 ngPCR – more cycles, more chance of contamination
27 Contaminated Positive Control ContaminationContaminated 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 ID’d Sutton as rapist; Sutton convicted and sentenced to 25 yearsRain from holes in roof of lab may have caused contaminationRecent retesting exonerated SuttonAlleles found: 1.1, 2, 4, 4.1One rapist: (2, 4)Other rapist must be: (1.1, 4.1)Sutton: (1.1, 2)Don’t overlook the obvious: Bob Blasier’s recent case
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)1 in 67 million
32 Independent TestingDifferent expert than consulting expert who reviews prosecution’s workResults of independent testingWhether to conduct independent testing is complicated judgment callFace possibility that exclusion may not occurAssume jury will find out you testedLab disclosesProsecution 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 expertsMay sound great but is it understandableExpert both good on merits and personableQuality Control – what has lab done to stop recent problems from occurring in its labAbility to Test – what could prosecution have tested but didn’t?
34 Presentation of the DNA Evidence at Trial with Jurors’ Perspectives in Mind
35 DNA Trial Counsel? Different viewpoints My viewpoint: You don’t have eyewitness counsel or informant counsel, so you don’t need DNA counsel. You don’t have DNA jurors, don’t have DNA counsel.If DNA Counsel – Counsel should be present entire trial
36 Presentation of DNA: Voir Dire Jury SelectionWhat do jurors think about DNA evidenceWhat do jurors think about OJ Simpson caseLearn about your jurorsEducate your jurorsOpen-ended questionsQuestionnairesGet 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 DNAIncorporate DNA evidence with rest of anticipated evidenceDon’t give away secretsDon’t talk about what you don’t understandDon’t bore the jury
38 Cross-Examination “Bias is Always Relevant” Don’t 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 questioni.e., don’t question credentials of prosecution witness who will admit to DNA transferQuestion the SCOPE of expert’s expertiseForensic scientist v. statistician
39 Practice Pointers Short, targeted cross-examination One fact per question, building upon each other, leadUse the jargon correctly – Don’t Use JargonKeep 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 prosecutor’s fallacy, right
40 Prosecution DNA Expert Do not spar!Don’t try to out-expert the expert; you’re an intelligent, well-informed layperson, not scientist, and jurors know that
44 Do You Call Your Own Expert? Differing opinion/interpretation of DNA resultsProsecution bears burden of proofSet Up battle of the expertsWhat will your expert say?You must understand DNA and talk about testimony with expert before expert testifies
45 Direct ExaminationDirect Examination should be about as long as attention span between breaks (1.25 – 1.5 hours)Includes qualificationsUse analogies and visualsTV, not radio, generationCinderella analogyExplain through questioning difference between your expert’s area of expertise and prosecution’s, and why that mattersPrepare expert for cross-examinationPrepare re-direct examination – LAST WORD!
46 Closing Argument Visuals? Yes, yes, yes. PowerPoint? No, no, no. Breaks downInflexibleFocus should be on the lawyer and the connection you have made with jury over course of caseSimple – Do not get overly technicalDemystify; bottom line, science v. artEmpower jurors
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