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ATTACKING SCIENTIFIC EVIDENCE Professor Ed Imwinkelried
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THE PARADOX The increasing using of expert testimony at trial VS. The alarming insights into the margin of error in expert testimony
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THE LARGE NUMBER OF POTENTIAL ATTACKS The Methods of Attacking Scientific Evidence (5 th ed. 2014)
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THE USES OF WITNESSES WHO HAPPEN TO BE EXPERTS --To testify to observed facts FRE 602 --To testify to lay opinions FRE 701 --To lecture about a general theory or technique FRE 702 (“or otherwise”) --To testify to an opinion derived by applying a general theory or technique to the facts of the case FRE 702 the syllogism
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THE SYLLOGISTIC STRUCTURE OF THE TYPICAL EXPERT’S DIRECT ---The witness’s qualification as an expert ---The validity of the general theory or technique (the major premise) ---The trustworthiness of the information about the case-specific facts (the minor premise) ---The application of the theory or technique to the case-specific facts ---The opinion (the conclusion)
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TARGET #1: THE WITNESS’S ALLEGED EXPERTISE An admissibility attack A stronger showing of the relevance of the witness’s qualifications to the specific issue before the court A weight attack The witness is a “Jack of all Trades.”
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TARGET #2: THE WITNESS’S CREDIBILITY An admissibility attack The importance of FRE 104(a) A weight attack A two-phase attack exposing the witness’s bias
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TARGET #3: THE WITNESS’S MAJOR PREMISE An admissibility attack Fujii, 152 F.Supp.2d 939 (N.D.Ill. 2000) Critically evaluating four aspects of the underlying empirical data A weight attack “The path not taken”
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TARGET #4: THE MINOR PREMISE An admissibility attack FRE 703 Williams, 132 S.Ct. 2221 (2012) A weight attack Outflanking the expert
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TARGET #5: THE APPLICATION OF THE MAJOR PREMISE TO THE MINOR An admissibility attack FRE 702(d) A weight attack Reasoning by mental health experts –DSM V (5 th ed. 2013) Reasoning by toxicologists—differential diagnosis (etiology)
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TARGET #6: THE WITNESS’S FINAL CONCLUSION An admissibility attack Forensic metrology – the need for confidence intervals A weight attack The lack of population frequency data The lack of baseline data
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TRIAL STRATEGY Admissibility How many targets? Weight How many targets? How many attacks on the target?
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CONCLUSION In the final analysis, the scientific method is essentially “commonsense writ large.” Sir Karl Popper, The Logic of Scientific Discovery 22 (1959)
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