Judges, Juries, and Judges, Juries, and Scientific Evidence - - PowerPoint PPT Presentation

20110330 20110330 1 1

Judges, Juries, and Judges, Juries, and Scientific Evidence Scientific Evidence

Valerie P. Hans Valerie P. Hans

報告人：簡凱倫 簡凱倫

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I ntroduction I ntroduction

  Most jurors are not screened for scientific

Most jurors are not screened for scientific background knowledge, and adopt a background knowledge, and adopt a predominantly passive role as fact predominantly passive role as fact-

• finders

finders within the adversary system. within the adversary system.

  How well do laypersons understand complex

How well do laypersons understand complex scientific and technical testimony presented scientific and technical testimony presented in this adversarial context? in this adversarial context?

  If they need help, how can jury assistance

If they need help, how can jury assistance be integrated into the unique setting of the be integrated into the unique setting of the jury trial? jury trial?

3 3

I ntroduction I ntroduction

  This article also reports the intriguing

This article also reports the intriguing findings of a new study involving state findings of a new study involving state and federal judges who watched clips and federal judges who watched clips

• f the same
• f the same mtDNA

mtDNA mock trial and mock trial and answered some of the same questions answered some of the same questions as the jurors. as the jurors.

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Complex Scientific Evidence and Complex Scientific Evidence and Jury Fact Finding Competence Jury Fact Finding Competence

  The agreement rates of judge and jury are

The agreement rates of judge and jury are similar in both straightforward and complex similar in both straightforward and complex trials, indicating that failure to understand trials, indicating that failure to understand the evidence is not a major determinant of the evidence is not a major determinant of judge judge-

• jury disagreement.

jury disagreement.

  Instead, many disagreements are explained

Instead, many disagreements are explained by the fact that compared to judges, juries by the fact that compared to judges, juries appear to require a stronger case by the appear to require a stronger case by the prosecution to convict the defendant. prosecution to convict the defendant.

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Complex Scientific Evidence and Complex Scientific Evidence and Jury Fact Finding Competence Jury Fact Finding Competence

  Case studies examining juror

Case studies examining juror comprehension of scientific testimony point comprehension of scientific testimony point

• ut the types of expert evidence that can
• ut the types of expert evidence that can

present problems for juries. present problems for juries.

  Richard

Richard Lempert's Lempert's review of thirteen review of thirteen complex trials concluded that even when complex trials concluded that even when juries did not completely understand all of juries did not completely understand all of the scientific details, jurors could usually the scientific details, jurors could usually comprehend enough of the testimony to comprehend enough of the testimony to engage in rational decision making. engage in rational decision making.

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Complex Scientific Evidence and Complex Scientific Evidence and Jury Fact Finding Competence Jury Fact Finding Competence

  Research suggests that judges might be

Research suggests that judges might be susceptible to various cognitive processing susceptible to various cognitive processing errors and biases, which in turn could errors and biases, which in turn could compromise their ability to make sound compromise their ability to make sound inferences. inferences.

  In sum, little work directly compares judge

In sum, little work directly compares judge and jury responses to the same scientific and jury responses to the same scientific issues. issues.

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Complex Scientific Evidence and Complex Scientific Evidence and Jury Fact Finding Competence Jury Fact Finding Competence

  Comparing judge and jury responses to the

Comparing judge and jury responses to the same material might highlight distinctive same material might highlight distinctive attitudes, skills, and abilities of judges attitudes, skills, and abilities of judges versus juries, which in turn could have versus juries, which in turn could have implications for structuring their decision implications for structuring their decision making and allocating tasks between them. making and allocating tasks between them.

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The Jury The Jury MtDNA MtDNA Study Study

  The mock trial, based on the facts and

The mock trial, based on the facts and evidence presented in evidence presented in State v. Pappas State v. Pappas, , included scientific expert testimony about included scientific expert testimony about mitochondrial DNA evidence. mitochondrial DNA evidence.

  The jury study used volunteers from the

The jury study used volunteers from the jury pool in New Castle County. jury pool in New Castle County.

  The jurors were assembled in groups of

The jurors were assembled in groups of eight and watched a videotape of the mock eight and watched a videotape of the mock trial. trial.

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The Jury The Jury MtDNA MtDNA Study Study

  The study varied whether mock jurors were

The study varied whether mock jurors were able to use specific trial reforms such as able to use specific trial reforms such as note note-

• taking, asking questions of experts,

taking, asking questions of experts, following a checklist, and using notebooks following a checklist, and using notebooks containing experts' slides and a glossary of containing experts' slides and a glossary of DNA terms. DNA terms.

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The Judge The Judge MtDNA MtDNA Study Study

  For practical reasons, judges read a

For practical reasons, judges read a short summary of background short summary of background information about the case. information about the case.

  Judges then watched video clips of the

Judges then watched video clips of the prosecution's expert, the defense prosecution's expert, the defense expert, closing arguments by both expert, closing arguments by both attorneys, and the judicial instructions. attorneys, and the judicial instructions.

11 11

The Judge The Judge MtDNA MtDNA Study Study

  The judges completed two

The judges completed two questionnaires, one before and one questionnaires, one before and one after watching the mock trial, that after watching the mock trial, that contained many of the same questions contained many of the same questions the mock jurors answered. the mock jurors answered.

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Judge and Jurors: Some Judge and Jurors: Some Background Differences Background Differences

  The juror represented a wide range of educational

The juror represented a wide range of educational levels: levels:

• - 2% who had not graduated from high school,

2% who had not graduated from high school,

• - 24% who had a high school degree,

24% who had a high school degree,

• - 30% who had taken some college courses,

30% who had taken some college courses,

• - 29% with college degrees,

29% with college degrees,

• - 14% who did post

14% who did post-

• graduate work beyond their

graduate work beyond their four four-

• year college degrees.

year college degrees.

  Judges were with college degrees and post

Judges were with college degrees and post-

• graduate law degrees.

graduate law degrees.

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Judge and Jurors: Some Judge and Jurors: Some Background Differences Background Differences

  For judges, the reported average was 10.29

For judges, the reported average was 10.29 courses across high school and college. courses across high school and college.

  For jurors, the reported average was 9.72

For jurors, the reported average was 9.72 courses (not statistically different ). courses (not statistically different ).

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Judge and Jurors: Some Judge and Jurors: Some Background Differences Background Differences

  33% of the overall juror sample, who possessed

33% of the overall juror sample, who possessed college degrees, reported an average of 14.04 college degrees, reported an average of 14.04 science and math courses (significantly more science and math courses (significantly more courses on average than the judges). courses on average than the judges).

  If science and math courses provide crucial

If science and math courses provide crucial background for the understanding of scientific background for the understanding of scientific evidence, then the college educated blue ribbon evidence, then the college educated blue ribbon jurors possess more of that background than either jurors possess more of that background than either the pool of judges or the full pool of jurors. the pool of judges or the full pool of jurors.

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Judge and Jurors: Some Judge and Jurors: Some Background Differences Background Differences

  When asked how much scientific evidence

When asked how much scientific evidence they had encountered in their work as they had encountered in their work as judges: judges:

• - 13% of jurors reported only a small amount,

13% of jurors reported only a small amount,

• - 66% recalled a moderate amount,

66% recalled a moderate amount,

• - 21% said they had a great deal of exposure.

21% said they had a great deal of exposure.

• - 7.9% of judges encountered "a great deal"

7.9% of judges encountered "a great deal"

• f scientific evidence in their judicial work.
• f scientific evidence in their judicial work.

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

  Before watching the video excerpts, jurors

Before watching the video excerpts, jurors and judges were asked to give their views and judges were asked to give their views about the reliability of DNA evidence: about the reliability of DNA evidence:

• - Judges averaged 4.49 on a 1 to 5 point

Judges averaged 4.49 on a 1 to 5 point scale, where 5 equaled extremely reliable, scale, where 5 equaled extremely reliable,

• - the jurors' average ratings of 4.56

the jurors' average ratings of 4.56

• - college educated jurors' average ratings of

college educated jurors' average ratings of 4.59. 4.59.

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

  We asked both judges and jurors how much they

We asked both judges and jurors how much they had heard about had heard about mtDNA mtDNA analysis before they analysis before they participated: participated:

• - A total of 52% of the jurors had heard nothing

A total of 52% of the jurors had heard nothing about about mtDNA mtDNA, compared to 25% of the judges. , compared to 25% of the judges.

  This circumstance is partly explained by the fact

This circumstance is partly explained by the fact that the jury study was conducted in 2003, when that the jury study was conducted in 2003, when the use of the use of mtDNA mtDNA evidence was beginning to be evidence was beginning to be

• used. Judges, on the other hand, were surveyed in
• used. Judges, on the other hand, were surveyed in

2007 2007

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

  Participants said it was easy to follow the

Participants said it was easy to follow the expert testimony about expert testimony about mtDNA mtDNA evidence: evidence:

• - 40% of the jurors,

40% of the jurors,

• - 50% of the college educated jurors,

50% of the college educated jurors,

• - 62% of the judges.

62% of the judges.

  Judges reported greater comfort with the

Judges reported greater comfort with the expert testimony than did jurors. expert testimony than did jurors. (significantly compared to the full jurors) (significantly compared to the full jurors)

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

  Participants understood the

Participants understood the mtDNA mtDNA well or well or very well after hearing the expert witnesses: very well after hearing the expert witnesses:

• - 47% of the jurors,

47% of the jurors,

• - 54% of the college educated jurors,

54% of the college educated jurors,

• - 55% of the judges. (not significantly)

55% of the judges. (not significantly)

20 20

Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

  Judges rated the defense expert as

Judges rated the defense expert as significantly more credible than did jurors. significantly more credible than did jurors.

  Judges may be more accustomed to the

Judges may be more accustomed to the adversarial and back adversarial and back-

• and

and-

• forth character of

forth character of expert testimony. expert testimony.

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

  Judges watched only portions of the videotaped

Judges watched only portions of the videotaped trial, whereas jurors watched the entire videotaped trial, whereas jurors watched the entire videotaped trial, including testimony by a police officer, an trial, including testimony by a police officer, an eyewitness, and the defendant. eyewitness, and the defendant.

  Interestingly, judges' estimates of the likelihood

Interestingly, judges' estimates of the likelihood that the defendant was the robber were that the defendant was the robber were significantly higher than those of the jurors (85% significantly higher than those of the jurors (85% versus 69% for all jurors). versus 69% for all jurors).

  Judges were also more likely to convict.

Judges were also more likely to convict.

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

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Reactions to the Mock Trial Reactions to the Mock Trial and and MtDNA MtDNA Evidence Evidence

  Both judges and jurors thought the

Both judges and jurors thought the mtDNA mtDNA evidence presented by the prosecution was evidence presented by the prosecution was very unlikely to be contaminated. ( very unlikely to be contaminated. (p p = .01) = .01)

  91% of judges rated the likelihood of

91% of judges rated the likelihood of contamination as not at all likely or only contamination as not at all likely or only slightly likely. The majority of jurors (76%) slightly likely. The majority of jurors (76%) responded the same. responded the same.

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  Eleven true

Eleven true-

• false questions tested the

false questions tested the participants' understanding of the participants' understanding of the basic science behind basic science behind mtDNA mtDNA and the and the understanding of inferences that could understanding of inferences that could be drawn from be drawn from mtDNA mtDNA evidence. evidence.

 

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  Overall judges and jurors responded

Overall judges and jurors responded similarly and accurately to most of the similarly and accurately to most of the individual items testing knowledge and individual items testing knowledge and inferences about inferences about mtDNA mtDNA evidence. evidence.

  Of eleven items, the responses were

Of eleven items, the responses were significantly different for three items and significantly different for three items and statistically indistinguishable on the statistically indistinguishable on the remaining eight items. remaining eight items.

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  One item produced the largest difference

One item produced the largest difference between judges and jurors: between judges and jurors:

• - "The

"The mtDNA mtDNA evidence in this case is evidence in this case is completely irrelevant because a substantial completely irrelevant because a substantial number of other people could also be the number of other people could also be the source of the hairs. source of the hairs.“

“

• - 51% of the jurors and 85% of the judges

51% of the jurors and 85% of the judges answered correctly. ( answered correctly. (p p< 0.01) < 0.01)

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  When asked whether the

When asked whether the mtDNA mtDNA evidence could evidence could have come from the defendant's brother if he and have come from the defendant's brother if he and the defendant had the same mother but different the defendant had the same mother but different fathers: fathers:

• - 90% of the jurors and 82% of the judges correctly

90% of the jurors and 82% of the judges correctly answered yes. ( answered yes. (p p= .04) = .04)

  It is interesting that jurors performed so well on

It is interesting that jurors performed so well on this item. this item.

  The jurors' superiority on this question as compared

The jurors' superiority on this question as compared to the judges' performance could well be due to the to the judges' performance could well be due to the fact that they deliberated and discussed the matter. fact that they deliberated and discussed the matter.

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  “

“Whether nuclear DNA or

Whether nuclear DNA or mtDNA mtDNA had the had the same ability to prove identity, or whether same ability to prove identity, or whether

• ne was superior to the other
• ne was superior to the other”

”:

:

• - Most jurors (89%) answered this question

Most jurors (89%) answered this question correctly, as did all but one judge. correctly, as did all but one judge. (significantly difference) (significantly difference)

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  College educated jurors, jurors with a

College educated jurors, jurors with a substantial number of math and science substantial number of math and science courses in high school and college, and courses in high school and college, and jurors with extensive job experience in math jurors with extensive job experience in math and science all performed better on the and science all performed better on the true true-

• false questions as compared to other

false questions as compared to other jurors. jurors.

  All three items in which the college

All three items in which the college educated jurors showed greater accuracy educated jurors showed greater accuracy than the judges. than the judges.

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  The responses were combined into an 11

The responses were combined into an 11-

• item

item MtDNA MtDNA Comprehension Scale. Comprehension Scale.

• - Each correct answer contributed one point to the

Each correct answer contributed one point to the scale. scale.

• - The full sample of jurors answered an average of

The full sample of jurors answered an average of 8.26 questions correct, 8.26 questions correct,

• - Judges answered a marginally higher average of

Judges answered a marginally higher average of 8.69 questions correct. 8.69 questions correct.

• - The college educated jurors answered 8.80

The college educated jurors answered 8.80 questions correct on average. questions correct on average.

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

  The comparison between the full juror

The comparison between the full juror sample and judges was marginally sample and judges was marginally significant: p = .101. significant: p = .101.

  The comparison between college educated

The comparison between college educated jurors and judges was not statistically jurors and judges was not statistically different. different.

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Judge and Jury Comprehension Judge and Jury Comprehension

• f the Scientific Evidence
• f the Scientific Evidence

35 35

Jury Trial I nnovations to I mprove Jury Trial I nnovations to I mprove the Jury the Jury’ ’s Comprehension s Comprehension

  To compare how different jury trial innovations

To compare how different jury trial innovations might help jurors master the details of scientific might help jurors master the details of scientific evidence, the Jury evidence, the Jury MtDNA MtDNA Study varied whether Study varied whether mock jurors could use: mock jurors could use:

• - note

note-

• taking,

taking,

• - ask questions about the scientific expert testimony,

ask questions about the scientific expert testimony,

• - use a checklist,

use a checklist,

• - employ a jury notebook containing the experts'

employ a jury notebook containing the experts' slides and a glossary of DNA terms, slides and a glossary of DNA terms,

• - or use multiple innovations.
• r use multiple innovations.

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Jury Trial I nnovations to I mprove Jury Trial I nnovations to I mprove the Jury the Jury’ ’s Comprehension s Comprehension

  We measured the impact of the use of these

We measured the impact of the use of these innovations on jurors' scientific understanding using innovations on jurors' scientific understanding using a subset of the true a subset of the true-

• false questions.

false questions.

  Two innovations produced small but statistically

Two innovations produced small but statistically significant benefits on jury comprehension: significant benefits on jury comprehension:

• - Jurors who were allowed to use checklists and jury

Jurors who were allowed to use checklists and jury notebooks did better on the true notebooks did better on the true-

• false questions.

false questions.

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Jury Trial I nnovations to I mprove Jury Trial I nnovations to I mprove the Jury the Jury’ ’s Comprehension s Comprehension

  Note

Note-

• taking was not associated with higher scores

taking was not associated with higher scores in this in this mtDNA mtDNA project. One likely explanation is that

• project. One likely explanation is that

the Jury the Jury MtDNA MtDNA Study was a relatively short couple Study was a relatively short couple

• f hours from start to finish.
• f hours from start to finish.

  The chance to ask questions did not improve

The chance to ask questions did not improve performance possibly because very few mock jurors performance possibly because very few mock jurors in the in the mtDNA mtDNA study availed themselves of the study availed themselves of the

• pportunity to ask questions of the experts.
• pportunity to ask questions of the experts.

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Conclusion Conclusion

  Research limitation:

Research limitation:

• - Because the group of judges had chosen to

Because the group of judges had chosen to attend a Science for Judges conference it is attend a Science for Judges conference it is quite likely they differed from their peers. quite likely they differed from their peers.

• - A strict comparison between jurors and

A strict comparison between jurors and judges is not completely fair to the judges judges is not completely fair to the judges who in real life can avail themselves of who in real life can avail themselves of numerous resources in trial decision making. numerous resources in trial decision making.

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Conclusion Conclusion

  Judges gave more credence to the defense

Judges gave more credence to the defense expert's testimony, yet were more expert's testimony, yet were more convinced that the convinced that the mtDNA mtDNA evidence was evidence was reliable and not contaminated. reliable and not contaminated.

  Another striking difference was that judges

Another striking difference was that judges saw the case against the defendant as saw the case against the defendant as stronger and were more likely to convict on stronger and were more likely to convict on the evidence. (affirm other studies) the evidence. (affirm other studies)

40 40

Conclusion Conclusion

  Two jury innovations in particular

Two jury innovations in particular-

• the use of

the use of jury notebooks and the use of a checklist jury notebooks and the use of a checklist-

• also increased jury comprehension.

also increased jury comprehension.

  This study found that the college educated

This study found that the college educated jurors possessed some fact finding jurors possessed some fact finding advantages over their juror peers with less advantages over their juror peers with less education, and even in some instances over education, and even in some instances over judges. judges.

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Conclusion Conclusion

  The significance of such educational factors

The significance of such educational factors leads one to consider the possible leads one to consider the possible advantages of employing blue ribbon juries advantages of employing blue ribbon juries in extremely complex trials. in extremely complex trials.

  Study find that the vigorous discussion

Study find that the vigorous discussion characteristic of diverse decision making characteristic of diverse decision making bodies also promotes fact bodies also promotes fact-

• finding.

finding.

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Conclusion Conclusion

  Does the value of using a special jury

Does the value of using a special jury

• utweigh the fact
• utweigh the fact-
• finding (and other)

finding (and other) advantages of a broadly representative advantages of a broadly representative jury? jury?

  That is an interesting question for

That is an interesting question for future research. future research.