Jurors and Scientific Causation: What Don’t They Know, and What Can Be Done About it?
12 Pages Posted: 21 Jun 2012 Last revised: 5 Oct 2012
Date Written: June 21, 2012
Past attempts to better equip jurors to comprehend scientific expert testimony have shown little success. This paper describes a new approach to training jurors to be better consumers of such evidence. In addition to assessing how well can jurors differentiate between valid and flawed experimental research when that research is presented through expert testimony in a civil trial, we describe an experiment that tests the efficacy of a new educational intervention designed to enable jurors to more capably evaluate causal scientific research. The intervention, which is brief, not case-specific, and transportable into trials of other causal issues, teaches jurors to understand and identify the three requisites of causal inference: temporal precedence, co-variation, non-spuriousness. Using 182 adult citizens as jurors, in a fairly realistic videotaped mock trial we presented a toxic tort trial in which the defendant’s product is alleged to cause a lung disease. The critical evidence is a study, presented by an expert, which tests that relationship through either a properly designed experiment or one in which one or another of the key elements of causal inference is absent. Consistent with previous researchers’ findings, untrained jurors were unable to distinguish the well designed experiment from any of the defectively designed experiments. However, trained jurors were better able to assess the quality of the research, and these more accurate assessments were reflected in their verdicts.
Keywords: Scientific Evidence, Causation, Juries, Education, Expert Evidence
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