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Comment by stepvhen | Hacker News Reader

5 years or so ago I was on a jury once concerning sexual misconduct, and spent a good hour or so in the deliberation scanning the submitted call records, looking for gaps in correspondence between the two relevant phone numbers. It was pretty easy to identify moments when the two parties were together, that's when they stopped texting, and checked they that matched up with all of the testimonies. They did, and it solidified a guilty verdict with my fellow jurors (sans one, on one count, but we had 7 already).

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That hinges strongly on the meaning of the word 'all' in your comment, if all is < 5 then that's not a very strong argument at all, if all is > 100 then it probably is (but it would still need analysis of a much larger volume of calls of pairs of phones to determine how often that situation would occur due to chance).

I should mention that it wasn't the only piece of evidence we looked over. We deliberated for around 6 hours I believe. Forgive me if I wasn't clear; I didn't intend to make it seem like I was the lone seeker of truth and made a grand argument to my peers; there was a lot discussed, by everybody. Also keep in mind that when you're on a jury, you only have so much to go on, and few resources with which to analyze. Thats why the phrasing is "beyond reasonable doubt."

I think if "only so much" is too little, and "few resources" are not enough, then you have no means to reach "beyond reasonable doubt", and you should say so.

Do you know the probability that this correspondence happened by chance?

I was convinced beyond reasonable doubt, having phone records that matched rather well with testimonies. I also might have fixated on it and ignored chance, but that's why there are 12 jurors.

If someone on HN ignores the statistics, what are the chances that the other jurors paid any attention to statistics?

Based on most of the posts here I'd say "someone on HN" is just as likely - if not more, due to misplaced confidence - to ignore statistics.

Reasonable doubt is not defined in terms of statistical confidence.

Maybe it should be.

Or all humans fall victim to largely the same kinds of fallacies. That's why there is no jury in all countries that I know of except America.

I'm not sure if a jury is a bad idea, when I first learned of it, I kinda liked the idea, but I'm worried about this kind of reasoning...

> That's why there is no jury in all countries that I know of except America.

The UK uses juries in much the same way as the US does, as do many other countries whose legal systems derives from that of the UK (which are a fair number, because colonialism.)

What do other countries do?

Is the decision made by one person that has these same fallacies? At least the risk is spread out some in the jury situation.

Other countries definitely use juries, just not as universally as the US. They more often just have a judge or a panel of judges, or sometimes a sort of jury that includes judges.

Proper training alleviates these fallacies. I trust a judge much better than a jury of random people.

On the other hand, the random jury doesn't have the same perverse incentives and web of relationships that support conviction.

Would you still trust that judge that was elected to office with lobbyist money?

I think electing judges might also be a uniquely American thing, and less than half the country does it. It's a much weirder practice than using juries. Obviously you can still say a judge was appointed by people elected with lobbyist money, but it's not that direct.

Might be my lack of knowledge in the subject, but I've never heard of electing judges. Isn't it just a study and a background check or so, at least in western Europe?

Not only do some states have elections, but they have partisan elections, which is just obviously a dumb idea. I have no idea how it works in other countries, but in most US states judges are either elected by the legislature or appointed by the governor.

Judges are not elected in my country, so can't comment on that.

This page contains a list of countries using Jury in various way.

https://en.wikipedia.org/wiki/Jury

Did any of the other jurors calculate the probability of the result being by chance?

I wonder if the defense attorney brought in a statician to argue that?

What a tragedy of justice that you used an absence of evidence as a deciding factor. There is so much logically wrong with that, even in correlation.

Suppose somebody's alibi is "I was driving between these two cities at the time, and then I spent the night working."

But their car-odometer didn't change, and their home-electricity usage dropped to zero that day.

Both of those observations are surely "evidence". Similarly, a digital signal still carries information, even though the zeroes are an "absence" of voltage.

Thats a lot different from "you weren't talking to someone, so you must have been doing X" Whereas in real life X could = anything.

The logic isn't even close:

Odometers increment on driven cars. The odometer did not increment. The car was driven. Unsatisfied.

People having sex are together. People who are together don't text each other. During a certain hour a person didn't text 68 contacts. At this certain hour, this certain person had sex with 68 people. Satisfiable.

It's more like: these two numbers are in constant contact all other hours of the day. At this hour midday, when others, including one of the relevant parties, say those two numbers are together, there is no correspondence. Later, the correspondence picks up as before.

You seem to be aware, at least on a subconscious level, of the larger point - as you've demonstrated by including additional evidence. The larger point being that the absence of phone records can, at best, disconfirm. There are far too many alternative explanations for it to be used alone or as confirmation.

Remember, in court we're not talking about logical proof (eliminating every alternative but the desired conclusion), but statistical proof (eliminating alternative conclusions with 51% or 95% certainty). Given an assumed or established statistical model of the probability of related events (e.g. knowing that a secretary at a business makes a log entry 99.9% of the time when she sends out a mailing), a non-happening (say the absence of a log entry) can easily establish a conclusion to the desired level of certainty.

Darn, I already replied to this point moments ago. There is a difference in the application of this logic in the court room where it can be challenged, and the juror room where it cannot - right?

I see your point of high probability they might have been together. But I don't see evidence for "sexual misconduct" during the time they were together. They could have just talked.

Anyway, the whole charge is disgusting. Leave them alone dammit.

There is nothing logically wrong with that. Evidence is anything that makes a conclusion more or less likely (in the Bayesian sense). All else being equal, knowing of a gap in an otherwise constant stream of communication makes a in-person meet-up more likely than it is without that knowledge.

Not every piece of evidence (in the Bayesian sense) is admissible in every court though, polygraphs being an obvious example. That is why courts get all pissy when jurors go off the reservation and start doing their own research. I'd be a little surprised if the judge in this case enthusiastically endorsed this sort of analysis going on in jury deliberation, but given your background - I'm interested to hear if I'm mistaken.

Evidence can be excluded if it's not relevant (in the Bayesian sense), or unreliable. You might have some argument that the phone records don't make the conclusion sufficiently more likely to warrant admitting it. But the bar for relevance is not high.

Moreover, this is kind of what juries do best: inferring what people did from other things they did or didn't do. While juries are subject to a lot of biases, I think humans have a good statistical model of the behaviors of other humans.

I guess I've been mistaken in my understanding of the whole process. I was under the impression that all the controls are in place specifically to restrict the juror's natural inclination to infer, because humans really suck at logical inference (and not just because of bias). I'd always assumed that an an innovation in natural language processing and combination with formal logic would be welcome in the court room, but it doesn't sound like that would be the case if empiricism is preferred to rationality.

This is just not true -- there are tons of highly informative, relevant kinds of Bayesian evidence that are excluded. For example, remaining silent, illegally-obtained evidence, hearsay, opinion of experts (in many cases).

The evidence is the phone record with a string of calls. A gap between calls is as much evidence as a phone call is. A gap is not absence of evidence.

What would you have used as a deciding factor? Often times circumstantial evidence is all there is to work with.

A case built on circumstantial evidence is the very definition of reasonable doubt and should be tossed out! I don't understand why so many people think the purpose of court is to convict people! You're question could litterally be reduced to "But how are we supposed to find them guilty if we don't have evidence?"

Ultimately, what is "reasonable doubt" is up to the jury.

I can't say I agree with the use of circumstantial evidence, but that's how the court works. Additionally, many people do get off based on lack of clear evidence?

It's off-topic, but I'm deathly curious - what kind of sexual misconduct is so serious that two people consensually meeting warrants a jury trial, complete with subpoenaed phone logs?

I suppose if one of them were underage...

Both parties were consenting, but one was underage at the time of the incident(s). The mother was the one who pressed charges, if I recall correctly.

Odd that the phone records were needed. If I thought the victim was telling the truth about beimg abused then the records wouldn't matter and if I had reason to doubt them then I don't see matching phone records satisfying the doubt.

> what kind of sexual misconduct is so serious that two people consensually meeting warrants a jury trial, complete with subpoenaed phone logs?

Their meeting up may have been consensual, but what happened while they were together might not have been. Also, the parent doesn't say both parties wanted to meet up. So, the meeting-up could have not been consensual. It could have been a stalking situation or maybe they just happened to run into each other by chance.

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