Are Juries About Guilt?

12 Angry Men is a classic movie that for many presents the ideal of a jury system of law.   An excellent Russian remake, 12, also seems to many re-affirm this idea.  The New York Post says “This is the rare remake that does honor to the spirit of the original” while the Austin Chronicle says:

12 is very bit as much of a moral powerhouse as its predecessors but with the added bonus of being simultaneously intellectually riveting and, at times, almost indescribably poetic.

It is indeed a good movie, and even reasonably true to human nature.  But if it presents an ideal jury, then it suggests juries are not about guilt.  To explain, I’ll need spoilers, which are below the fold.

The film begins with only one juror voting against guilt, and ends with them all voting against.  Along the way every vote change but one is toward a not-guilty verdict, and the one change toward guilty is very clearly not based on any evidence about the guilt of the accused.  This pattern is very suspicious.  Even setting aside the issue of a lack of Aumann-like agreement based on being persuaded by others’ opinions, a Bayesian’s opinion path should be a random, not a linear, walk.

The first piece of even indirectly relevant evidence about the guilt of the accused is not mentioned until a half hour into deliberation, and that evidence is that the defending attorney does not seem very competent.  It takes a full hour of deliberation to finally mention some directly relevant evidence, which is that the murder weapon isn’t as rare as the prosecution claimed.

So what do they talk about if not evidence relevant to guilt?  The main dynamic seems to be shifting coalitions based on various kinds of ethnic and group identities, and based on specific dominance and submission status moves within the jury.   The accused is mainly a canvas on which jurors can negotiate to paint a group portrait of themselves.

We are proud of juries because they show that “we” are in charge, even if we have to negotiate who “we” are.  Our power over the accused validates our authority, and the accused can be declared guilty or innocent depending how close and loyal they are to “us.”  If 12 is a guide, juries about about group identity, not guilt.

Added:  I’m talking about the ideal of a jury – why people think it is a good system.  I can believe most real juries spend most of their time discussing relevant evidence.

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  • http://blog.greenideas.com botogol

    I have been in two juries. It was a fascinating experience, not a bit like that movie. Both juries talked extensively about the evidence: the main preoccupation was whether the prosecuting counsel had done enough to makes us ‘sure’ of guilt.

    All sorts of alternative explanations of the evidence against the accused were considered for plausibility, both juries entertaining all manner of outrageous defences that were not in any way suggested by the defence counsel (eg could the drugs have been dropped coincidentally from the window of a passing train?)

    Both juries were surprising, at time infuriating, and unpredictable. But in my judgement they were about guilt.

  • http://blog.greenideas.com botogol

    …and about (I meant to say before the comment escaped) about particularly about *proof of guilt*

  • http://fasri.net Robert Bloomfield

    Wait, they’re not about signalling? I thought everything was about signalling. Well, I guess that is what happens when you draw conclusions from you own assertion that a fictional account of a jury is ‘ideal.’ Perhaps that isn’t a very reliable method.

    Ah, those slow summer news days…..

  • Mike

    Reid Hastie’s done good work on the group dynamics of juries.

    botogol – while the deliberations may nominally be about guilt, there’s a lot of interplay into how seriously we take each of the people in the room, the implied judgments they all make about the defendant that aren’t explicitly spoken….

    I think if it were really about guilt and not about group identity formation you’d see a lot more hung juries, no?

  • K. Larson

    I must say, arguing determinants of jury behavior from Hollywood Evidence seems a bit… thin.

    Might we be able to say that juries are “about guilt” when jurors perceive the rewards to signaling probity/justice are higher than the rewards to signaling in-group loyalty?

    One can easily imagine cases where signaling adherence to group norms (voting to convict child molester) might net higher payoff than showing even-handedness.

    Does this imply inflection points past which the jury system fails?

  • http://www.jackchristopher.com Jack Christopher

    If judgment is mostly about status signaling. But not only about status, at what point would flipping a coin give better outcomes (on average)?

  • Jonathan

    This is a really thought-provoking post. I’d like it if you could talk more about this in future posts, perhaps as it related to psychologists’ group polarization theory.

  • http://blog.greenideas.com botogol

    @mike – yes, no doubt there is some of that, but in my (anecodatal experience) it didn’t seem to be dominant.
    What did surprise me was the importance of process over fact: my juries were less concerned with did-he-do-it (they thought he probably did) and more concerned with was-the-case-proven-to-an-appropriate-standard-of-proof.

    perhaps people were signalling their legal sophistication.

  • jimmy

    “…a Bayesian’s opinion path should be a random, not a linear, walk.”

    True, but..

    If you select for the few cases where everyone changes their mind (perhaps because it makes a better movie), it very well could look ‘linearish’.

    Many people will find a few stocks that look to be increasing roughly linearly and then buy them assuming it’s linear, when really its just brownian motion selected for *looking* linear.

    • http://hanson.gmu.edu Robin Hanson

      I’ll bet most zero-mean-move unit-step-size random walks between 11 and 0 have more than one move in the other direction.

  • Psychohistorian

    “I’m talking about the ideal of a jury – why people think it is a good system.”

    …or, just perhaps, twelve guys talking solely about evidence would make an interesting ten-minute movie or a very boring two-hour one. There’s no basis for calling this how an ideal jury should function – there is no pretension that its members are ideal jurors. The beauty of the film is that despite human imperfection, the facts win out. If the jury were ideal, i.e. composed of ideal jurors, the movie would be ten minutes long. It’d be like a Bond movie where the villain shoots Bond in the head as soon as he’s captured.

    Group identity is relevant; if social norms required that people think like the holdout juror, then the movie would be something of a tragedy. But social norms dictate that the facts win out, and that’s exactly what happens. It is precisely because our society wants the facts to win out over identity politics that this is seen as a good movie with a positive ending. The fact that it takes a certain amount of politics to get real people to change their minds is a brute fact about how people think (in this case, taken to extreme for dramatic effect), not a normative claim about how juries should ideally operate.

  • Unnamed

    There is a lot of research out there on jury decision making. One fairly thorough paper by Devine and colleagues is available here in rtf format (although the tables aren’t included; to see them you need to have electronic access to the journal). One thing that the paper shows (in table 6, which is unfortunately not in the free version) is that the 12 Angry Men scenario is very rare: the jury’s verdict after deliberation is usually what the majority of jurors thought before deliberation. When the jurors are split 11-1 before they start deliberating (or 10-2 or 9-3), they almost never end up agreeing on the minority verdict (though they may end up hung, especially when 2 or 3 jurors favor acquittal). (One caveat: much of this evidence comes from mock juries rather than real juries, but that’s still better than fictional juries.)

    There are several other relevant findings discussed in the paper, mostly in the section with the heading “Deliberation Characteristics”:
    – There is some evidence of a momentum effect, with more and more jurors changing their minds in the same direction, but there is also evidence that this could be due to the information that is discussed rather than social pressures.
    – “[J]urors spend most of their time talking about the facts of the case, the judge’s instructions, and the expressed verdict preferences of members.”
    – Strength of evidence has a big impact on verdicts, and other variables are most likely to matter when the evidence doesn’t strongly favor either side.
    – Jury forepersons tend to be high status, and their views do have a disproportionate influence on the amount awarded in cases with monetary damages, but there isn’t much evidence that they have extra impact on verdicts.

  • http://blog.greenideas.com botogol

    The most important thing to ponder is why it is that we don’t allow (in the UK, and I understand also in the US) research into real juries.

    It would be a simple matter to film jury deliberations for later analysis (either covertly or – now that we are all so used to being filmed, even with the jury’s knowledge) but this type of research isn’t allowed.

    It’s as if the authorities don’t *want* to know how – or whether – the jury system works. Now *that*’s interesting, why would that be? If you were runnnig the judicial system wouldn’t you want to know how it worked?

    One might say that the jury *system* is not about justice.

    • Constant

      Well, there are some good reasons for making jury deliberations secret. Similarly, as far as I know we do not violate the secrecy of the voting booth for research, instead gathering data indirectly such as by exit polling.

      • http://blog.greenideas.com botogol

        sure, but there are also some good reasons for doing research.
        the jury could be filmed. the tape archived until the judicial process is over and any sentence completed, then anonymised (court official bleep out names or something) and then rleased to selected researchers. I don’t think anyone’s rights would be seriously violated. Hey, you could ask the defendant for his/her permission.

  • jonathan

    I was on a jury which had an 11-1 vote for conviction which reversed to acquittal. The fiction in the movie, from my experience, is that it happened for dramatic effect over time. In our case, we began to review the evidence again – and then again – and someone noticed a new point about the gun at issue. We all looked at the gun and realized collectively that we couldn’t see if there was a serial number and thus it was unfair to convict a person for having a gun without one because there was no proof – no evidence at all – that he knew it was missing. The vote on that count went immediately to 12-0 for acquittal and I suspect that most such changes are cascades of 1 or 2 steps.