The prosecution are only going to bring a case if they think they can get a conviction, i.e. prove it beyond the jury’s reasonable doubt. In effect, the prosecution are another jury, but one subject to several biases compared with the real jury:
self-serving assessment of how good their case is
illusion of transparency
priming by evidence they have which for one reason or another cannot be used in court
regression to the mean.
So in general we should expect jurors to have a lower estimate of the prosecution’s case than the prosecution themselves do.
In addition, cases only go to trial that are contestible—where the prosecution thinks it can be proved beyond reasonable doubt but the defence does not. When the case is overwhelming and the accused is actually guilty, the accused is more likely to plead guilty without a trial. Jurors will never see those cases, only those that the accused finds worth contesting.
So it is not surprising that in a substantial proportion of cases, nobody can be sure of the jury’s verdict until it is announced.
In addition, cases only go to trial that are contestible—where the prosecution thinks it can be proved beyond reasonable doubt but the defence does not.
Or in cases where the defendant is, you know, actually innocent. Some people find that they can’t stomach the idea of pleading guilty to a crime they didn’t commit, whether or not they can prevail in court.
And cases when the penalty after going to trial is likely to be the same as the penalty after a guilty plea. If the sentence is mandatory life, might as well roll the die and hope you get the jury that doesn’t believe confessions, DNA, ballistics, or eyewitnesses.
In addition, cases only go to trial that are contestible—where the prosecution thinks it can be proved beyond reasonable doubt but the defence does not.
And it’s worth noting that the fraction of cases that go to trial is quite small. The best statistics I could find was the table in EXAMINING THE WORK OF STATE COURTS, 1998 page 72. Out of all criminal cases, the prosecutor or court dismisses 18.4%, the accused pleads guilty in 63.4%, and only the middle 3.7% go to trial. (There is also a mysterious 14.5% “other” category...).
Of course, these percentages do not directly reflect the state of the evidence: because of plea bargaining there is an expected utility calculation involved as well.
The prosecution are only going to bring a case if they think they can get a conviction, i.e. prove it beyond the jury’s reasonable doubt. In effect, the prosecution are another jury, but one subject to several biases compared with the real jury:
self-serving assessment of how good their case is
illusion of transparency
priming by evidence they have which for one reason or another cannot be used in court
regression to the mean.
So in general we should expect jurors to have a lower estimate of the prosecution’s case than the prosecution themselves do.
In addition, cases only go to trial that are contestible—where the prosecution thinks it can be proved beyond reasonable doubt but the defence does not. When the case is overwhelming and the accused is actually guilty, the accused is more likely to plead guilty without a trial. Jurors will never see those cases, only those that the accused finds worth contesting.
So it is not surprising that in a substantial proportion of cases, nobody can be sure of the jury’s verdict until it is announced.
Or in cases where the defendant is, you know, actually innocent. Some people find that they can’t stomach the idea of pleading guilty to a crime they didn’t commit, whether or not they can prevail in court.
And cases when the penalty after going to trial is likely to be the same as the penalty after a guilty plea. If the sentence is mandatory life, might as well roll the die and hope you get the jury that doesn’t believe confessions, DNA, ballistics, or eyewitnesses.
And it’s worth noting that the fraction of cases that go to trial is quite small. The best statistics I could find was the table in EXAMINING THE WORK OF STATE COURTS, 1998 page 72. Out of all criminal cases, the prosecutor or court dismisses 18.4%, the accused pleads guilty in 63.4%, and only the middle 3.7% go to trial. (There is also a mysterious 14.5% “other” category...).
Of course, these percentages do not directly reflect the state of the evidence: because of plea bargaining there is an expected utility calculation involved as well.