DOI: 10.3886/icpsr04356.v1
title: Testing the Effects of Selected Jury Trial Innovations on Juries' Comprehension of DNA Evidence in New Castle County, Delaware, 2003
title: Version 1

description: This study tested whether the use of selected jury trial
 reforms enhanced jurors' understanding of complex and challenging
 scientific evidence presented during a criminal trial. The study
 examined the use of several jury reform techniques using a controlled
 mock jury approach in which mock juries composed of jury pool members
 watched a videotaped armed robbery trial featuring conflicting expert
 testimony about mitochondrial DNA (mtDNA) evidence. A total of 480
 mock jurors were randomly assigned to eight-person juries and to one
 of the six conditions in the experiment. Ten mock juries were run in
 each of the six conditions (No Innovations, Note Taking, Question
 Asking and Note Taking, DNA Checklist and Note Taking, Jury Notebook
 and Note Taking, and All Innovations). At various points throughout
 the study (before the trial, after watching the videotaped trial, and
 after reaching a verdict), mock jurors were asked to complete
 questionnaires to gauge their understanding of mtDNA and the mtDNA
 evidence presented during the trial. They were also asked if and how
 the use of the jury trial innovations helped in their understanding of
 the mtDNA evidence. Specific variables contained in the study include
 demographic variables of the mock jurors, including their math and
 science background, mock jurors' views of science, their understanding
 of mtDNA, their perceptions of the reliability of different types of
 evidence, and the credibility of the prosecutor, defense attorney,
 detective, eyewitness, defendant, and expert witnesses, and whether
the mock jurors favor or oppose the various innovations.
description: The purpose of this study was to test whether the
 use of selected jury trial reforms enhanced jurors' understanding of
 complex and challenging scientific evidence presented during a
 criminal trial. This study combined the need for scientifically
 reliable data regarding the effects of jury trial reforms with the
 ongoing search for ways to improve juror understanding of DNA
 evidence. It was the first study of forensic evidence involving
mitochondrial DNA (mtDNA) rather than nuclear DNA (nDNA).
description: In this experimental research study, 480 mock
 jurors were randomly assigned to eight-person juries and to one of the
 six conditions in the experiment. Ten mock juries were run in each of
 the following six conditions: Condition 1 -- No Innovations (Control),
 Condition 2 -- Note Taking (Control), Condition 3 -- Question Asking and
 Note Taking, Condition 4 -- DNA Checklist and Note Taking, Condition 5
 -- Jury Notebook and Note Taking, and Condition 6 -- All Innovations
 (Note Taking, Question Asking, DNA Checklist, and Notebook). The
 checklist (Conditions 4 and 6) listed the principal questions about
 the mtDNA in the case, but left it for the jurors to fill in the
 answers. The notebook (Conditions 5 and 6) included background
 materials on the mtDNA issues. At the beginning of the study,
 demographic and background information were collected from the mock
 jurors as well as the participants' attitudes toward science in
 general and DNA evidence in particular. Then all 60 juries watched the
 same videotaped armed robbery trial. Rather than construct a mtDNA
 case from scratch, the mock trial was based on the issues, fact
 pattern, and transcripts of testimony from an actual trial, State
 v. Pappas. The nonscientific factual evidence was modified so that it
 was more ambiguous, making the mtDNA evidence more crucial to the
 jury's decision. The trial lasted 70 minutes, including one ten-minute
 break. In the two conditions in which questions for the experts were
 permitted (Conditions 3 and 6), the judge in the videotaped trial
 instructed the jurors on the procedure for asking questions of the
 expert witnesses. The research assistants repeated the instructions
 and invited questions after each of the scientific experts testified.
 If a juror had a question, he or she wrote the question on a sheet of
 note paper and turned it in to the research assistant. Judge Dann
 ruled on the admissibility of all questions. If the question was ruled
 admissible, Judge Dann or Professor Hans then called one of the DNA
 experts who had previously agreed to field calls and obtained a verbal
 response to the question. Judge Dann or Professor Hans wrote down the
 response verbatim and returned it to the jury at the next opportunity.
 Following the trial, but before jury deliberations, the mock jurors
 were asked to complete a second questionnaire that asked questions
 about the mtDNA and their use of and attitudes toward the jury
 reforms. There was a specific questionnaire for each condition, as
 items about the individual reforms differed from condition to
 condition. Once the mock jury had reached a unanimous verdict or had a
 mistrial declared because of a hung jury, all participants completed a
 third questionnaire. The mock jurors were asked about their reaction
 to the jury's verdict, their own individual views, mtDNA questions,
 and support for different jury reforms. A set of questions was added
 to this final questionnaire after a highly publicized mtDNA
 evidentiary hearing that occurred during the study, to determine
participants' exposure to the hearing and any impact it may have had.
description: Variables found in this study include demographic
 variables of the mock jurors, such as age, gender, race/ethnicity,
 level of education, number of math and science courses taken in high
 school and college, job experience in math or science, current job
 status, job category, political views, household income, and if the
 mock jurors had ever served on a jury for a criminal or civil
 case. They were also asked questions to judge their knowledge and
 understanding of mtDNA and the mtDNA evidence presented in the trial,
 as well as question about their general views of science. Mock jurors
 were asked to rate the reliability of police evidence, victim
 evidence, expert evidence, DNA evidence, and eyewitness evidence. They
 were also asked to rate the credibility and believability of the
 prosecutor, eyewitness, detective, the prosecutor's expert witness,
 defense attorney, the defense attorney's expert witness, and the
 defendant. Mock jurors were asked whether or not they used the
 innovations available to them in their specific condition and why they
 had decided to use the innovation or not. Finally, the mock jurors
 were asked whether they favor or opposed the use of each innovation,
 regardless if it had been available for their personal use in the
study.
description: none
description: Response Rates: Between October 14, 2003, and December 16, 2003, a
 total of 3,381 jurors reported for jury duty. The volunteer rate was
 assessed on four separate days by calculating the proportion of
 volunteers to the total number of jurors present. The volunteer rate
 was an average of 74 percent, ranging from a low of 64 percent to a
high of 97 percent.
description: Presence of Common Scales: Several Likert-type scales were used.
description: Participants in this study were volunteers randomly
 selected from the pool of potential jurors who were not needed for
 actual trials. The source list for potential jurors in New Castle
 County, Delaware is the current list of the county's registered
 voters, drivers' license and identification card holders. A total of
 3,381 jurors reported for jury duty during the period of the study,
 from October 14, 2003, through December 16, 2003. On some days, very
 few or no cases went to jury trial, and the volunteers never went
 through the jury selection process. On other days, most of the
 remaining jurors had gone through at least one jury selection and had
 not been selected. Once the need for actual jurors was met, staff
 members randomly selected a set of jurors from their master list of
 the remaining jurors who had previously volunteered for the mock jury
 study. On most days, there were 16 volunteers who were randomly
 divided into two groups of mock jurors. The overall nature of the
 study was then described to the jurors, who were given consent forms
 and were able to ask any questions about the study prior to agreeing
to participate.
description: Datasets: 
DS1: Testing the Effects of Selected Jury Trial Innovations on Juries' Comprehension of DNA Evidence in New Castle County, Delaware, 2003
description: All jury-eligible adults called to jury duty at the New
 Castle County Courthouse in New Castle County, Delaware between
October 14, 2003, and December 16, 2003. Smallest Geographic Unit: none
description: on-site questionnaire