26 September 2010

The Impact of Race On Jury Verdicts

This paper examines the impact of jury racial composition on trial outcomes using a unique dataset of all felony trials in Sarasota County, Florida between 2004 and 2009. . . .

We find strong evidence that all-white juries acquit whites more often and are less favorable to black versus white defendants when compared to juries with at least one black member. . . we find strong statistical evidence of discrimination on the basis of defendant race. These results are consistent with racial prejudice on the part of white jurors, black jurors, or both.

Using a simple model of jury selection and decision-making, we replicate the entire set of empirical regularities observed in the data, including the fact that blacks in the jury pool are just as likely as whites to be seated. Simulations of the model suggest that jurors of each race are heterogeneous in the standards of evidence that they require to convict and that both black and white defendants would prefer to face jurors of the same race.

From here (it is notable that two of the three authors are economists and that none are law school or criminal justice department faculty).

The paper itself lays out the facts with greater specificity:

On average, jury pools include twenty-seven potential jurors, of which seven are seated as part of the jury (including alternates). Because the eligible jury population of Sarasota County is less than four percent black, there are no blacks in the jury pool about half of the time and no blacks on the seated jury in over 80 percent of the trials. Our research design exploits the variation in the composition of the jury pool across trials, which is primarily driven by which eligible jurors in the county are randomly called for jury duty on a given day. We provide strong direct evidence that the composition of the jury pool is quasi-random, demonstrating that the attributes of the jury pool are uncorrelated with the characteristics of the defendant and the criminal charges. . . .

[T]he presence of even one or two blacks in the jury pool results in significantly higher conviction rates for white defendants and lower conviction rates for black defendants. In cases with no blacks in the jury pool, 84 percent of black defendants are convicted and 68 percent of white defendants are convicted. But, when the jury pool includes at least one black potential juror, conviction rates are nearly identical at 72-74 percent, and when the jury pool includes two or more blacks, conviction rates reverse: 86 percent for white and 77 percent for black defendants.

The dataset included 401 felony jury trials, in which "38 percent of the defendants are black and 55 percent are white."

One key implication of the study is that the percentage of blacks in the jury pool strongly influences conviction rates in the aggregate. This is consistent with previous studies that have shown that a more representative jury pool reduces conviction rates in states that change their jury pool selection process.

This is not a trival implication because blacks are almost always underrepresented to some extent, on average, in jury pools for particular trials. This may be, in part, because the populations from which jury pools are called are not representative due to factors like differing voter registration or driver's license rates and felony disqualification rules, and, in part, because of below average appearance in court to serve on juries.

For example, about one in six residents of Sarasota County, Florida is black, but only 4% of jurors in the county are black.

Does culture matter?

This study, and much of the prior empirical literature on jury verdicts in criminal cases involves Southern states.

It would also be interesting to see if this conclusion applies with equal force outside the South. Politically, race has a much stronger influence on the political identity of whites in the South, who are overwhelmingly Republicans and are overwhelmingly conservative, than in the North, where whites are not monolithic politically and where whites in urban areas, where black defendants most often face jury trials outside the South, tend to be politically liberal.

One way to interpret the stronger link between race and political identity and ideology in the South is that Southern whites have a stronger sense of racial identy and solidarity generally than whites elsewhere, which influences the impact of the racial composition of a jury on the conviction rate of those juries to a greater degree than it would elsewhere.

Are There Panel Effects?

At first glance, the data also appears to show strong "panel effects," something previously identified by political scientists looking at decisions made by multi-judge panels, which show that panels with people of multiple views tend to produce moderate results even when one view or another has a majority that could be imposed upon other panel members). A lot of the impact of jury pool composition on outcomes appears to come from changes in the deliberation process, rather than from raw exercises of political power.

Another fact that at first seems to suggest that the observed differences are psychological rather than political is that in "the subset of trials where blacks are present in the jury pool, trial outcomes are more favorable to black versus white defendants regardless of whether a black juror is actually seated."

But, the authors make a strong case that lawyers for the prosecution and defense simply strike the potential jurors least favorable to their case and that jury pools with some black members favorable to their case are statistically more likely to have a middle members, in terms of likelihood to convict by striking jurors who they believe would not be favorable to them. In other words, even if all black jurors on the pool are struck, pre-emptory challenges used to remove them from the jury pool force the jury selected to be more heavily biased towards pro-defendant white jurors than it would be otherwise. Black jurors in the jury pool, whether or not they are seated in this model, affect the result by influencing the likelihood of conviction of the median juror.

In fact, there are panel effects (as opposed to having results dominated by hold out jurors since unanimous verdicts are required), but the only panel effect seems to be a "majority effect" something quite different than what is seen in multi-member judicial panels where the median vote does not explain outcomes well:

[W]hatever the majority position is at the beginning of deliberations predicted the eventual verdict 90% of the time. Subsequent literature has continued to substantiate this. We incorporate this majority effect into our model by assuming that whatever position (acquittal or conviction) is in the majority becomes the eventual unanimous verdict. Thus, in the example above, where four of the seven jurors vote to convict, the eventual unanimous decision is a conviction. Note that implementing the majority effect implies the median juror is the deciding factor.

Beyond the majority effect, however, there do not appear to be panel effects:

Another potential explanation for the results we see is that whites behave differently when they are in a jury pool with another black. This would result in large changes in conviction rates when one black is added to the pool. This explanation seems unlikely, however, because we have already documented that whether blacks get on the seated jury has no effect.

What About Death Penalty Cases?

It isn't clear to what extent these outcomes apply to death penalty cases. On judicial panels, "panel effects" disappear in death penalty cases and judges instead vote their conscious regardless of who else is on the panel with them (one of the very few kinds of cases where this happens).

If the study's analysis is correct, "death qualification" of juries (the U.S. Supreme Court allowed practice of removing from juries in death penalty cases jurors who categorically oppose the death penalty), should, in theory, greatly increase the likelihood of conviction of black defendants and greatly decrease the likelihood of conviction of white defendants, in cases where the death penalty is sought, by changing the makeup of the pool from which jurors are drawn, and should also significantly reduce the likelihood of a hung jury in death penalty cases.

The seven capital case trials in the five year period were excluded from the study. But, one shouldn't automatically assume that this is the case because the death penalty is sought in many where a jury is unlikely to impose it for strategic reasons to increase the likelihood of a plea bargain to a serious charge and to increase the likelihood that a jury will convict as a result of its "death qualification," even if the facts of the case make it unlikely that the jury will actually impose the death penalty in that case.

Prior studies have shown similar effects when looking at the racial composition of the jury itself, in the likelihood of a jury to impose the death penalty in capital cases and in the likelihood of juries to convict in non-capital cases.

A Footnote On Hung Juries

The dataset they use treats a hung jury as an acquittal, but they suspect that hung juries are rare in Sarasota:

The National Center for State Courts conducted a survey of hung jury rates using felony case data from all federal courts and 30 state courts in 75 of the most populous counties. The NCSC project found that state courts in large urban areas had an average hung jury rate of 6.2%, with substantial variation across courts, ranging from a low of .1% in Pierce County, Washington to a high of 14.8% in Los Angeles County, California. Federal hung jury rates were found to be particularly low, averaging about 2% of all federal jury trials: federal civil trials had lower rates than federal criminal trials. One possible explanation for the low hung jury rate in civil trials is the fact that civil juries typically have just 6 members while many courts have 12 jury members for a felony trial. Given that Sarasota non-capital felony trials have 6-member juries, we would expect the hung jury rate in Sarasota to be on the low end of the spectrum.

Batson In Light Of The Empirical Evidence

This data suggests that U.S. Supreme Court rules that give special attention to the use of preemptory challenges to create all white juries in cases with black defendants are actually not as important as they might seem, while constitutional rules that require jury pools to take certain steps to make them representative of the community aren't as important as they should be.

Batson comes into play only after a jury pool is chosen and lawyers begin the jury selection process, and this appears empirically to have an approximately 35% impact on the likelihood that a black juror will be seated, but the fact that a black juror is seated turns out to have little impact on whether or not a jury will convict, the presence of that juror in the jury pool is what appears to produce the impact on the conviction rate empirically.

The study also suggests that while juries are influenced by race in making their decisions, that the process of selecting juries from the jury panel by lawyers and judges is not strongly racially biased, that it is modestly biased in favor of black jurors in the pool to the extent that there is racial bias, and that a lack of racial bias by attorneys is not inconsistent with their role as advocates for the state and the defendant respectively.

In other words, it appears that lawyers do generally comply with Batson, despite the fact that it is often be hard to prove a violation of it in practice, not because it has symbolic value, but because lawyers try to reach a maximally beneficial result for their clients. The appearance of all white juries in Sarasota appeared in five years of data to reflect little more than random chance, given the jury pool, despite the fact that the jury selection process itself is not actually random.

The study also provides some empirical guidance regarding the impact of larger juries in non-capital cases. The study suggests that the only real impact of a larger jury on the results is that it increases the size of the jury pool from which it is drawn, thus reducing the number of juries that differ significantly from the average for the population from which the jury pools for individual trials are drawn somewhat. This would not change the average number of convictions much, if at all, but a larger jury pool would reduce the extent to which the outcome was influenced by the race of the jurors in the jury pool chosen for the trial, by making those jury pools more homogeneous on average.

The model developed in the case also suggests strongly the death qualification is very unfair to criminal defendants in murder cases where the death penalty is sought, making them much more likely to be convicted on the same facts in cases where death is sought than similarly situated defendants in cases where it is not sought, and giving prosecutors a strong incentive to seek the death penalty for strategic reasons, even in cases where they don't sincerely believe that it is actually justified.

Few Criminal Cases Are Hard Ones

The study also seems to imply that the outcome is clear in about than four out of five of felony cases in Sarasota, Florida that go to trial rather than producing a plea bargain. A minimum of 68% of cases where convictions results and a minimum of 14% of cases that produce acquittals are sufficiently clear than the racial composition of the jury doesn't matter. Given that something like 90% of cases produce plea bargains generally, and that plea bargains are usually made before a jury pool is drawn, the random impact of the racial makeup of the jury pool that is selected for a case in Sarasota, Florida only directly matters in about 2% of all criminal prosecutions.

An average juror of either race would reach the same aquittal or conviction decision in about 55% of cases involving black defendants and about 68% of cases involving white defendants. So, more than half of felony criminal cases that go to jury trials are exceedingly clear.

The Model Used

The precise model developed to fit the data follows a normal distribution of the percentage likelihood that a juror will convict someone of a particular race and that the median juror in the jury pool will be the median juror in the selected jury. The numbers in that model were as follows:

[For White defendants,] White jurors are drawn from a truncated normal distribution with mean 0.68 and standard deviation 0.75, while black jurors are drawn from a truncated normal distribution with mean 1.1 and standard deviation 0.3. For white potential jurors, the relatively high standard deviation results in large mass points at both zero and one and the distribution between zero and one is relatively flat, thus spreading the required standards of evidence for white jurors pretty thinly. On the other hand, the distribution for black jurors is much tighter (with a large mass point only at one) and located largely in the upper half of the white distribution. . . .

[F]or black defendants[,] [w]e assume that white jurors are drawn from a truncated normal distribution with mean 0.9 and standard deviation 0.7, while black jurors are drawn from a truncated normal distribution with mean 0.45 and standard deviation 0.4. . . . Note that the bulk of the black juror distribution now lies in the lower tail of the white juror distribution. . . . A random black member of the pool is seated about 120 percent as often as a random white member. Again this matches the data quite well – as blacks in the jury pool are about 135 percent as likely as whites to be seated when the defendant is black.

Let's translate that into English. The variability of conviction rates among whites is much greater than the variability of conviction rates among blacks, and the amount of variability is quite similar for both propensity to convict white defendants and propensity to convict black defendants for both white jurors and black jurors.

But, the average likelihood of conviction varies greatly between white and black jurors and depends a great deal on the race of the defendant.

If the simple model is accurate, and it does reproduce the actually results from which it is derived quite well, the average white juror will initially vote to convict a white defendant 68% of the time and a black defendant 90% of the time. The average black juror will initially vote to convict a white defendant 100% of the time and a black defendant 45% of the time.

The average white jurors are twice as likely as the average black juror to initially vote to convict a black defendant. The average black juror is about 50% more likely to initially vote to convict a white defendant as a black defendant.

The study, of course, says little or nothing about why white jurors and black jurors have such different propensities to convict defendants of particular races, but it does suggest that the differences in how different jurors initially evaluate the evidence are stark.

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