Juror Unanimity Isn’t Necessarily a Great Thing: A Guest Post

Thanks for putting up with my quirky intellectual agenda of friendship and the law in the last two posts. For my final post, I thought I would highlight a more traditional area of my legal research: the jury.

There is something quirky at play here too: the U.S. is one of the few democracies around the world to have a unanimity rule for juror decision-making. The Times’s Adam Liptak has been doing a series on American Exceptionalism — “commonplace aspects of the American justice system that are virtually unique in the world” — but he has yet to focus on the puzzling persistence of unanimity as our jury decision rule.

Here are a few facts that make unanimity a non-obvious choice for juror decision-making.

1) We don’t require unanimity for any other important decision in our pluralistic polity. Our Supreme Court doesn’t decide by unanimity and neither do our legislators.

2) No other modern country (save Canada and a few jurisdictions in Australia) requires it.

3) We require unanimity to acquit as well as convict, so the idea that it contributes to protecting defendants is not fully accurate.

4) The symmetrical unanimity requirement contributes to inefficiency by giving us hung verdicts more than necessary.

5) Our juries have gotten more diverse as we’ve made it harder to get out of service and as we’ve grown more inclusive in our political system. With that diversity, majoritarianism seems more appropriate.

6) Empirical evidence tends to support the view that verdicts don’t change all that much when you change the decision rule. So the idea that unanimity contributes to certainty is probably overblown.

7) There is also empirical evidence suggesting that people assigned a unanimous decision rule will often agree to decide by supermajority (albeit unanimously) — meaning that in such cases, there is no difference between the two rules, except that some jurors agree to pretend that they agree with a verdict from which, in fact, they may strongly dissent.

8) We all know that many people are willing to falsify their preferences by changing their votes to agree with the majority; the incentives for doing so are especially high when one is a holdout juror being berated by other jurors because everyone wants to get home faster.

9) We don’t have such stringent unanimity rules in the context of the civil jury or courts martial, yet both those systems are respected and deemed legitimate by the public. Moreover, the few states that have experimented with relaxed jury-decision rules for the criminal jury — Oregon and Louisiana — do not suffer especial deficits in legitimacy.

10) Unanimity is often an illusion. Suppose a jury hangs, leading to a retrial. The second jury empanelled to try the defendant then convicts unanimously. Despite this second “unanimous” verdict, the truth is that, of a total of 24 jurors who heard the evidence, fewer than 24 were persuaded to convict. Indeed, it’s possible in theory that only thirteen — a bare majority — were persuaded, if in the first trial the holdout favored conviction, not acquittal.

These facts should be enough to get us to question our fealty to unanimity. At the very least, I think it is high time we stopped requiring unanimity for acquittals.


The effect on deterrence should be taken into account. Increasing the burden of proof for conviction lowers the price of crime. So you could have a situation where an alternative causes ten people to be wrongly convicted, but reduces the number of murders by fifteen. Assuming we considered being falsely convicted (perhaps for the death penalty) and being murdered to be about as bad as each other, this would pass a cost-benefit analysis.

Ethan Leib


The argument is not that we ought to follow all other countries (though the founders didn't make up our regime out of nothing: they learned the separation of powers from political theorists before them -- and theorists from other countries, too). It is simply that we ought to question our own practices in light of the fact that many highly developed and humane democracies (with arguably more just criminal justice systems than ours) don't do it this way. Indeed, we copied unanimity from another country (the UK). Now that the source country has backed off, maybe we ought to think about doing it too. The key here is open-mindedness. I despise the closed-minded.


How I despise the "no other country does it this way argument". How many democratic republics existed in 1789? I suppose that since no other country did it that way that the US was in error? I suppose the "great experiment" never would have happend in a world where our founders were supposed to look around and take a pole of how every other country ran their government.


Given the method of selecting juries, unanimity is essential since there is seldom more than one intelligent person on a jury.


i don't think "rather let 100 guilty men free than convict one innocent man" makes economics sense, no system is perfect, what if the price of taking out 100 guilty men is one false positive?

say we convict an innocent 20 year old, we'll ruin max. 70 years of his life, it's unfair but i strongly believe society is better off than choosing the system where 100 guilty go free. Do we really think each one of them will only ruin (70/100) max. 0.7 years of someone's life?

rapists will take at least 10 years of each victim (for recovery) and murderers will do even worse, even non violent crimes like fraud can ruin people for many years (making them poor)

it's the same principle with soldiers, it's unfair that so few get hurt or die defending a country of millions but society is better off risking their lives than accepting the consequences of defeat.

Ethan Leib

The "empirical evidence" is cited and considered in the longer versions of the arguments:



Most of it is not available for linking. This is a blog, people. I'm just offering some food for thought and some provocations to get us to question a widespread practice many of us take for granted. In any case, I'm glad to see that no one has yet come to the defense of the unanimity rule for acquittals. That, to my mind, is the craziest thing we do -- and I'd be most happy to see that change first.

Lewis J Birns

7) There is also empirical evidence suggesting that people assigned a unanimous decision rule will often agree to decide by supermajority (albeit unanimously) — meaning that in such cases, there is no difference between the two rules, except that some jurors agree to pretend that they agree with a verdict from which, in fact, they may strongly dissent.

Maybe I'm not so bright. Could somebody explain what the above means ?

Windsor Detroit

Here's an idea, everyone who is willing to give up their right to a traditional trial by jury sign a statement to that effect and mail it in to your county sheriff.

I've written mine out, I've even waived my right to trial. If they so much as suspect I may have done something wrong, or even don't like me very much, they can go ahead and blow my brains out. If everyone did the same, perhaps by means of a 'click through' statement attached to a website this country would be much more efficiently governed.

You do read every word of the 'terms of use' when you agree to them, don't you?

Ishmael Noone

I think the only real test is whether we, as a defendant, would want to require a unanimous verdict. This must be done before we make decisions for others. Would our preference change if we were guilty or innocent?


One of the most interesting things about juries is that they can decide to completely ignore a judge's instructions. If the judge says, "If the evidence shows that the defendant killed Mr. Jones, you must find the defendant guilty of murder," and there is video evidence of the defendant doing just that, I understand that the jury CAN STILL decide to find the defendant not guilty (perhaps based on the fact that he was killing someone who molested his child, say). I LOVE THIS! It truly puts the power in the people's hands, and out of the hands of judges who often will jail a good man and turn lose an evil man.

Some churches use "unanimity" in a similar way: If the majority votes YEA, they all agree to go with a "unanimous" YEA vote. It's partly about appearance, I imagine, but also about creating some degree of unity.

I do think that in particulary heinous crimes, if say 10 of the 12 think a person is guilty, that should carry the day. Why? Because otherwise we risk putting someone out on the streets who is a predator. I'm not talking about someone who shot his wife in bed with her lover, but a predator type (serial killer, rapist, etc.).

Just my take on it. I might feel different if I was the one being accused.

At the least, perhaps there is a intermediate something that can be done. That is, a person doesn't get the full sentence, but perhaps they get some sort of probation, or wear a ankle bracelet, etc. Only in these particularly heinous instances, though.



The "jury system" is indeed absurd. In my experience on trial juries, getting home quickly is the single most pervasive persuader in the room. In my experience on a grand jury, the persistent lying of police officers and detectives is so blatantly obvious as to have motivated the majority of people in the jury box of the grand jury I sat on to refuse to indict one "defendant" after the next. Indeed, having raised the question of why accused citizens are called defendants in a grand jury chamber, given that they are not yet indicted, drew a scornful response from an Assistant District Attorney. In the end, my jury was hectored by the District Attorney himself, and several of us who posed the most challenges to the nonsense being presented to us as evidence were given early walking papers. Our justice system is so broken issues like jury unanimity are pointless. We would do better to adopt the practice of investigating magistrates. There is no justice in America. Isn't that obvious?



Theory also argues that unanimity can be worse (e.g. Fedderson and Pesendorfer, 1998).

Ethan Leib

As I wrote, Greg:

"Moreover, the few states that have experimented with relaxed jury-decision rules for the criminal jury — Oregon and Louisiana — do not suffer especial deficits in legitimacy."

Do people read before they shoot off their mouths?


I feel that it is unfair to ask a member of the public who was not convinced beyond a reasonable doubt that a man was guilty to take part in his conviction. The system now ensures that nobody has to take part in what they believe to be the conviction of an innocent man.

I would propose for acquittals that if a majority of jurors is convinced on a balance of probabilities that the accused is innocent, that should be sufficient to establish a reasonable doubt. However, if a majority simply have what they beleive to be a reasonable doubt, and the rest are convinced the man is guilty I think a new trial is in order.


since when do juries "vote for acquittal" I always understood that they vote on the question of: is the defendant guilty? If not, then the result is aquittal, but the vote was on a question of guilt, not innocence. Innocence is presumed (or is supposed to be).


The only reason I hate reading this blog is that it forces me to care about things I hadn't thought about. You've put forth a very compelling argument against unanimity, and now I'd have to say that I'm against it too.


Guy Wms

It seems to me that this "article" is entirely unworthy of the fine replies posted here. That is to say, a lackluster effort at best.

Certainly I am no expert but isn't the intent behind the unanimous jury more of a political safeguard? In any event it is indeed a point of pride for our nation.



Great post, Steve @60.

Regarding this quote (#4 from post 57):

"Think about it this way: people who are in the superminority (lone holdouts, or small groups of holdouts) only have a real incentive to debate and discuss if they think that they can get the verdict of their choice (since they can just get a hung jury result by shutting up). When they see that they have to convince everyone else in the large majority, they are inclined to shut down."

Where does this information come from? That does not hold true from my multiple juror experiences (both being the one convinced and being the one doing the convincing). It also does not hold true for people I have interviewed about their juror experiences--even for the holdout people who ultimately "gave up"--they did NOT go quietly.

I would really like to know who are these holdout jurors who are silently causing hung juries. Please post this info!



In preserving the integrity of the justice system, institutional considerations are every bit as important as the decision-science dynamics. Unanimity in criminal trials gives an appearance of fairness which lends credibility to the principles of justice-as-fairness which underpin our legal system.

The institutional costs of unanimity in criminal trials pale in comparison with the benefit of institutional credibility. And, if your arguments about jury decision-making dynamics are correct, then the perceived costs of unanimity are every-bit as small as perceived decision-making benefits your analysis so deftly minimizes.


I'm not persuaded.

I doubt it would be wise to casually dismiss the system developed by our forefathers who, I don't doubt, were well aware of the tendency of the majority to exert its will on the minority.

Our system is rooted in our own particular history and reflects centuries of experience and judgments. The fact that other "modern" (one wonders what backward legal artfices might be lumped into the mix) systems are not like ours does not suggest to me that they are doing something right and we something wrong. My experience with western European legal systems is they are inordinately trustful of the legal process as a science and perhaps too willing to trust the government to prosecute. Our system of laws is one area where the US clearly has done better than most of Europe.

Also citing Louisianna to suggest a majority-rule system can work well is pretty weak. The author is also fairly well wrong that there are not unanimous principles at work in other important areas of our government. The president's veto power, the vice-president's tie-breaking power in the Senate and the equitable power that judges have to set aside a jury verdict are all examples of a unanimity principle (of a sort - and also suggestive of the many very undemocratic principles that we wisely adhere to).

Most troubling is the assumption that efficiency and certainty suggests that majority rule is enough. Having a unanimity principle is intended to make it harder to convict a person wrongfully. Only one person has to be reasonably doubtful that the government has met its burden. We are not talking about having a tolerance for the usefulness of a manufactured item. This relates to allowing the government to deprive a person of her liberty.

The entire analytical construct used here is off kilter.