The best and worst times to have your case reviewed by a judge

Recently, I’ve been working my way through Daniel Kahneman’s fascinating book on human decision making, “Thinking, Fast and Slow.” In the third chapter, Kahneman discusses how external factors can affect our tendency to fall back on easy “default” decisions instead of taking a few minutes to think the decision through. To drive his point home, he provides one disturbing example from a research article published in PNAS a few years ago.

In this article, the researchers analyzed 8 experienced judge’s decisions on parole requests as a function of time of day. The judges reviewed about 35 cases per day, spending about 6 minutes on each case. On average, the judges approved only 36% of the parole requests presented to them each day, so the chances of having a positive judgement on your case are already bleak.

Now, we’d expect judges — of all people — to be the best at making impartial decisions. If no external factors were affecting their decisions, we’d expect to see them consistently approving about 36% of the parole requests throughout the day.

Let’s take a look at what the researchers found.


Proportion of parole requests approved as a function of what order they were reviewed in.
Each tick on the x-axis denotes every third case.
Circles denote when the judges took a food break. Source

Shockingly, the judges appear to be much more inclined to approve a parole request when they’ve just come off a break. In contrast, they reject far more requests than usual the closer they get to break time — and nearly 100% of the requests just before they take a break.

This study provides a classic example of depletion effects in human judgement, a theory which suggests that we have a limited amount of mental energy to expend during a working period. The longer we work on mentally strenuous tasks, the more mental energy we expend, and eventually we’ll run out and start falling back to these easy — and often wrong — default decisions.

In the judges’ case, once a sufficient number of cases had worn them down, they started defaulting to rejecting every case put in front of them until it was break time. That means that perfectly eligible prisoners had to spend even more time in prison because the judge hadn’t eaten his mid-morning snack.

Yet more proof that humans don’t make decisions in a vacuum: even missing breakfast can alter how you approach the day.

The take-away here?

  • Try your best to be seen by judges first thing in the morning or just after lunch.
  • Take regular snack breaks throughout your workday; the longer you work without a break, the worse you perform.

Dr. Randy Olson is a Senior Data Scientist at the University of Pennsylvania, where he develops state-of-the-art machine learning algorithms with a focus on biomedical applications.

Posted in data visualization, review Tagged with: , , , ,
  • nobody

    I wonder about the BMI of these judges.

    I like your conclusions, but the might only apply to overweight, older men with blood-sugar issues. Insulin resistance can be a bear, and make you perform sub-optimal compared to a normal non-diabetic who doesn’t need a snack.

    • I don’t think they looked at the weights of the judges, but 6 of the judges were males and 2 were female. You can find more details in the open access article.

  • Alex

    I fell for the sexy appeal of this study, then half way through writing about it, I realized that the study missed a very mundane explanation for the striking results.

    Explanation here:

    • That’s an interesting explanation that I’ve heard a couple times since posting this. People with good lawyers (and therefore good chances of having a positive decision on their case) tend to go first after the break. Thanks for linking it!

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  • Lorenzo Ruzzene

    Cool! Just wondering, the judge can’t decide which cases to deal with? I mean, starting the day with the “easiest” ones, for example?

    • Regardless of the order in which the judge deal with the cases, the bias remains. But seeing that even simple mental tasks such as chosing which links to click exhausts mental power, I would prefer judges to do difficult cases first and then easy cases when bloodsugar is low.

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  • asdf 323

    The judge at 5pm does not want to make the mistake of releasing a dangerous criminal. He has no time to read the documentation. To protect his social position he will prefer to err on the side of caution.

  • Seth

    That is NOT the only possible explanation – I’ll give you a few off the top of my head: Judges get frustrated with seeing so many criminals, and tend to be harsher the more they see. Judges tend take breaks after they’ve seen people they judge negatively. Judges set easy cases (either the easy paroles or rejections) at the start/end of their shifts. There I’m sure exist better explanations too. You’ve shown a correlation, you’re overextending by claiming causality.

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  • John Doe

    As a practicing attorney, I think the ultimate conclusion is correct, but the data does not necessarily support it. In my experience, cases are decided in descending order of the amount of time they are expected to take, with the most contentious ones decided last. The easy ones are decided first, and in cases of parole decisions, since there is zero incentive for an inmate to agree not to be paroled, the first cases decided will be those where there is an agreement by the state to parole. Once those are done, the hard ones, where it is less likely that parole will be granted are heard.

    The list basically re-sets after each break as deals are worked out.

    Again, as a practicing attorney, I agree with the conclusion, but not with the suggestion that this data necessarily supports it.

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