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Presentation on theme: "ATTACKING SCIENTIFIC EVIDENCE Professor Ed Imwinkelried."— Presentation transcript:


2 THE PARADOX The increasing using of expert testimony at trial VS. The alarming insights into the margin of error in expert testimony

3 THE LARGE NUMBER OF POTENTIAL ATTACKS The Methods of Attacking Scientific Evidence (5 th ed. 2014)

4 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

5 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)

6 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.”

7 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

8 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”

9 TARGET #4: THE MINOR PREMISE An admissibility attack FRE 703 Williams, 132 S.Ct. 2221 (2012) A weight attack Outflanking the expert

10 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)

11 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

12 TRIAL STRATEGY Admissibility How many targets? Weight How many targets? How many attacks on the target?

13 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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