This is a fun discussion. My take is that the testimony is barred. Of course it is about her mental state. That’s why it’s probative. If it were not probative of her mental state, then it would not be admissible.
Plus, it’s too loosey-goosey. In Michigan, I see police officers routinely testifying to the effect that the defendant intended to distribute dope based on the quantity or packaging. There is no meaningful opportunity to cross examine the officer’s experience that purportedly supports the opinion. Same with testimony re the value of controlled substances.
We would never get away with such flimsy expert credentials in civil litigation.
I frankly never understood why juries ever find this testimony persuasive. They knew coming into the trial that the police thought the suspect was guilty or they wouldn't have brought them to trial. All such testimony does is lay out the particulars of why they felt that.
Indeed, I'd argue that this kind of police expertise testimony is presumptively prejudicial because the jury has already factored in the fact (supposed to or not) that the police judged the suspect to be guilty so it's being double counted.
Perhaps I am naive, but I don't think the rules of evidence should ever permit any expert to opine, either implicitly or explicitly, as to someone's state of mind. To me, this isn't a matter of policy or text. It is, instead, the result of presuming innocence until guilt is proven. If guilt requires intent, then the prosecution's job is to prove to the jury - - the trier of fact - - that intent was present. Some facts may require expert testimony. And of course experts can disagree, which will always leave the jury trying to determine which expert view to accept as fact. But experts should never be allowed to opine on matters that are outside their area of expertise. And no one is an expert in something that requires time travel and mind reading - - going back in time to the moment at which the incident occurred and determining what was or was not inside the mind of the defendant. I understand the potential conflict between "policy" and "text", but to my unlawyerly mind, this case presents no conflict. Text and policy are uniform - - both clearly prohibit an expert, even one that is credentialed in the human psyche, from opining as to state of mind.
One final point, as someone who has served as a juror on more than five criminal and civil cases: the vast majority of jurors will place an enormous amount of weight on both the implicit and explicit views of an expert. That is even more true when that expert is a member of law enforcement because, for all our faults, we remain a nation of "law and order" adherents. I have been present in the jury room when some jurors have tried to disregard expert testimony in favor of their own world view. But even those jurors assert that they agree with the expert - - they simply twist the expert's view to conform to theirs. All the more reason to insure that the expert doesn't opine on topics that are outside their expertise.
I am from a different professional background, but I really enjoy reading these analyses of questions.
This particular question has me puzzled though. In the Diaz example, One would presume that cross of the expert testifying that virtually all drug couriers are aware of their cargo would include direct question of whether the Expert had interrogated Ms Diaz. If he had not as indicated, then why could not his testimony be stricken as irrelevant? I read a story once about a cow jumping over the moon and virtually all of the children I attended preschool with believed that story to be true. But... what does that testimony have to do with me, the person on trial for jumping over the moon unlawfully? That an expert who has not established reason to believe that Diaz knew she was transporting drugs believes Diaz was transporting drugs because he believes most mules know without completely documented evidence introduced demonstrating that an impossibly low percentage of mules do not know does not establish anything about Diaz. It would be the same as saying that since 80 precent of mules are Mexican, that of and by itself is probable cause to stop and search any Mexican, a situation which would of course be as impossible to justify as saying the 20 percent of mules remaining were Americans and also justifying their search. It would seem to me that the expert's testimony could be reduced to nothing more than speculation. and uninformed speculation at that by a trained attorney.
Yes the question of Rule 704(b) remains, but from what I see of the discussion, good lawyering should pretty much render the rule unnecessary because it would seem to be very counter productive to get into that territory.
A few years ago, I wrote a paper in Judge Easterbrook's Legal Interpretation class on precisely this issue--the paradox of outcome (aggregating each justice's overall disposition) and issue (aggregating each justice's stance on individual issues) voting systems. Splintered plurality opinions in complex cases (see National Pork case from last term) demonstrate how cycling (see public choice theory) can create a seemingly arbitrary result where conflicting minority opinions can produce majority results. It's challenging to feel confident one way or another about which system is "better" (whatever that means). Ultimately, I concluded that outcome voting (the Court's current approach, as moderated by the Marks rule when you have a plurality) was superior because it better safeguards against strategic behavior; in a pure issue voting system, a justice might be tempted to strategically vote dishonestly on one issue if he or she cares deeply about the overall outcome. Also, we generally don't expect alignment of reasoning (as required in issue voting systems) in virtually any other voting system, such as juries voting to acquit or convict, congressmen voting up or down on legislation, or friends trying to vote on which restaurant to visit for dinner. In those situations, the overall disposition of each voter--as determined by each person's distinct reasoning--is what matters the most, and I'm not so sure why the legal system is any different. Outcome voting also solves (or at least mitigates) the challenge you pose in this post: issues can be broken into sub-issues and sub-sub-issues (into infinity), and if we prioritize alignment of reasoning the most, why stop at the first layer of issues? A final thought I've been exploring more recently is whether focusing too excessively on the abstract can undermine the Supreme Court's fundamental duty to resolve cases and controversies of disputing parties. Put differently, by turning too far away from disputing parties and focusing only on abstract coherence (a sort of choose your own adventure thought experiment) of reasoning and not the overall disposition, isn't the Court undermining the justice owed to the disputing parties right before them? I've never heard anyone raise this point before, so it's likely wrong or misconceived, but I haven't heard many satisfying answers when I raise point this in legal circles. Thanks for the thought-provoking post.
Are juries supposed to be better at evaluating the evidence? I thought the jury trial was supposed to be a defense against tyranny not epistemically superior (and other countries experience skipping juries seems to back this up as does my experience on them).
Absolutely fascinating! In a short amount of time, this is already becoming one of my favorite Substacks.
My take on the matter: Even though I think the officer's testimony is sort of bullshit and that Diaz should not have been convicted if that was indeed the key factor motivating the jury, I don't believe that the testimony should be barred on basis of 704(b). To me, what distinguishes this case from Trump v. Anderson case is simple, and how to resolve the tension between arbitrary distinction and atextual expansion is about the spirit of the law:
In Trump v Anderson, I cannot think of a single reason why the Fourteenth Amendment would've been written to exclude presidents. That this is even a discussion feels like a simple oversight, and therefore, the pro-disqualification side should win.
With 704(b), however, there's a clear benefit to be had from experts providing testimony regarding general probabilities. This benefit may be marginal, and it may have its other drawbacks (e.g., by being too persuasive), but saying something like "In 99.99% of cases, drug mules are knowing participants" imparts information. (It's especially clear when you imagine a different percentage--what if drug mules were knowing participants only in 75% of cases?) This is a statistic, in some ways a fact, which puts it in contrast to psychologists' speculations about a person's interiority. (I say "in some ways" a fact, because statistics can be so easily and so often twisted or misunderstood by lack of context or lack of Bayesian reasoning.)
What I suspect we need is new rules or legislation around the usage of statistics in testimony, and that would make the 704(b) issue no longer matter.
I’m quite dubious of the AI recommendation. I thought the article was interesting for showing how deep the rabbit hole goes, even for a simple question.
It seems to me that the difficulty comes from wanting consistency, because there are so many things that a ruling could be consistent with in so many ways. Considered as a standalone policy question, it seems simpler: how much evidence should we require for punishing someone as a drug mule? Is finding a large amount of fentanyl in the car enough evidence, or is more needed to avoid punishing unwitting drug mules? Even if that possibility is rare, it should be considered. Perhaps punishment should be less without having further evidence of intent?
A legislature considering the policy question should probably take into account how drug smuggling currently works, with better evidence than one expert’s opinion. And then, also take into account how criminals respond to incentives, and that’s going to be a guess. Tactics change.
It seems like the court system isn’t a great place to have this policy debate, because everything becomes a consistency argument, including consistency with rules that are quite far removed from how best to fight drug trafficking without punishing innocent people.
As a non-lawyer (who teaches psychology to pre-law students), I want to say I really enjoyed the Juror Ids and Egos post, as it gave great context to our class discussions on how judges have no idea how jurors evaluate evidence. I'll have to add this to the reading list too!
SCOTUS will of course affirm. The whole concept of experts testifying about the MOs of drug traffickers is absurd and outrageous. Who is the defendant supposed to cross examine—some opinion-haver who knows nothing of this defendant or the actual people who secreted the drugs?
I don’t have a law background, but as an American it seems absurd that we would ever accept evidence of the form “People like x usually also are y”, because inherently there is always reasonable doubt. Statistical arguments should never be admissible in court, only direct fact based ones. Similarly, since psychology tells us that memories are often fallible, we should never accept witness testimony except in the most blatant cases (“I saw her fire the gun and then get caught by the officer, without losing sight of her”). There is a huge degree of doubt introduced by these types of arguments, and we shouldn’t let prosecutors get away with providing any doubt.
Really never? So you can basically never sue tobacco or asbestos companies because the proof of causation is entirely statistical? Even DNA evidence is ultimately based on a statistical claim about inadvertant matches.
A well-defined appropriate statistical result is, imo, far better than most trial testimony. It's just that statistics is hard and most people don't understand the subtleties.
Really our common sense is also a kind of statistical argument as well.
Hmm, I guess I underdefined "statistical argument". I'm fine with group statistical arguments - saying "there's a 50% chance for smoking to cause death, multiplied by 1,000,000 smokers, so smoking killed around 500,000 people, plus or minus some number" - but not individual statistical arguments - "this person smoked, smoking kills 50% of smokers, so smoking killed this person" (or even "smoking kills 98% of smokers, so smoking killed this person"). Statistical arguments are also more fine in civil cases than criminal cases, when there only needs to proven preponderance of the evidence, rather than proof beyond a reasonable doubt.
Perhaps the Supreme Court could define a statistical chance for what "beyond a reasonable doubt" means - does it need a 99% chance? 99.9%? 99.99%? But without a number defining what that cutoff should be, it's easy for a prosecutor to portray a relatively low chance as being essentially certain.
I think the problem that this issue goes to is: what do you do about evidence that can be absurdly strong (stronger than anything we infer by common sense) but for which most jury members and judges just aren't familiar enough with to understand when it's genuinely strong or a subtle fallacy.
I mean we can't demand that only mathematicians sit on juries. At the same time it seems crazy to say that you can't introduce really irrefutable proof because someone might claim to have it when they don't.
It might be fine if it wasn't the case that the defense is rarely able to hire the expert to evaluate it...maybe allow it in criminal cases only if the government pays for a decent defense statistics expert to throughly review the claims.
But if you want a wrongful death judgement the law demands you prove causation. For good reason, you can't argue that there is a 1% chance that roundup killed your spouse and get 1% of the damages. So those cases kinda have to take statistical evidence and determine that it exceeds some sufficient threshold.
Sure, beyond a reasonable doubt is a higher standard but now that you have the principle are you really going to say there is no threshold?
"You claim not to have had any contact with the deceased at all but every week you play the lotto with random numbers and we found a notebook with her name on it with a page titled lotto numbers and each week those numbers exactly match the tickets we found in your drawer"
Work it out and the chance that it's a coincidence is far far less than the absurd theory someone who just happened to look exactly like you drove up in the same model car you drive and shot your girlfriend in front of witnesses.
We may not know exactly where that threshold is legally but that doesn't mean there aren't clear cases. As the above illustrates in some sense all testimony is a stat judgement (all the witnesses didn't just happen to have a seizure that caused them all to hallucinate the same thing).
Re: DNA evidence they should be more careful but I thought it's now more an issue of transfer since everyone moved to longer profiles after UK false positive...but maybe still damaged profiles are an issue.
This is a fun discussion. My take is that the testimony is barred. Of course it is about her mental state. That’s why it’s probative. If it were not probative of her mental state, then it would not be admissible.
Plus, it’s too loosey-goosey. In Michigan, I see police officers routinely testifying to the effect that the defendant intended to distribute dope based on the quantity or packaging. There is no meaningful opportunity to cross examine the officer’s experience that purportedly supports the opinion. Same with testimony re the value of controlled substances.
We would never get away with such flimsy expert credentials in civil litigation.
Thanks for the discussion.
I frankly never understood why juries ever find this testimony persuasive. They knew coming into the trial that the police thought the suspect was guilty or they wouldn't have brought them to trial. All such testimony does is lay out the particulars of why they felt that.
Indeed, I'd argue that this kind of police expertise testimony is presumptively prejudicial because the jury has already factored in the fact (supposed to or not) that the police judged the suspect to be guilty so it's being double counted.
Perhaps I am naive, but I don't think the rules of evidence should ever permit any expert to opine, either implicitly or explicitly, as to someone's state of mind. To me, this isn't a matter of policy or text. It is, instead, the result of presuming innocence until guilt is proven. If guilt requires intent, then the prosecution's job is to prove to the jury - - the trier of fact - - that intent was present. Some facts may require expert testimony. And of course experts can disagree, which will always leave the jury trying to determine which expert view to accept as fact. But experts should never be allowed to opine on matters that are outside their area of expertise. And no one is an expert in something that requires time travel and mind reading - - going back in time to the moment at which the incident occurred and determining what was or was not inside the mind of the defendant. I understand the potential conflict between "policy" and "text", but to my unlawyerly mind, this case presents no conflict. Text and policy are uniform - - both clearly prohibit an expert, even one that is credentialed in the human psyche, from opining as to state of mind.
One final point, as someone who has served as a juror on more than five criminal and civil cases: the vast majority of jurors will place an enormous amount of weight on both the implicit and explicit views of an expert. That is even more true when that expert is a member of law enforcement because, for all our faults, we remain a nation of "law and order" adherents. I have been present in the jury room when some jurors have tried to disregard expert testimony in favor of their own world view. But even those jurors assert that they agree with the expert - - they simply twist the expert's view to conform to theirs. All the more reason to insure that the expert doesn't opine on topics that are outside their expertise.
I am from a different professional background, but I really enjoy reading these analyses of questions.
This particular question has me puzzled though. In the Diaz example, One would presume that cross of the expert testifying that virtually all drug couriers are aware of their cargo would include direct question of whether the Expert had interrogated Ms Diaz. If he had not as indicated, then why could not his testimony be stricken as irrelevant? I read a story once about a cow jumping over the moon and virtually all of the children I attended preschool with believed that story to be true. But... what does that testimony have to do with me, the person on trial for jumping over the moon unlawfully? That an expert who has not established reason to believe that Diaz knew she was transporting drugs believes Diaz was transporting drugs because he believes most mules know without completely documented evidence introduced demonstrating that an impossibly low percentage of mules do not know does not establish anything about Diaz. It would be the same as saying that since 80 precent of mules are Mexican, that of and by itself is probable cause to stop and search any Mexican, a situation which would of course be as impossible to justify as saying the 20 percent of mules remaining were Americans and also justifying their search. It would seem to me that the expert's testimony could be reduced to nothing more than speculation. and uninformed speculation at that by a trained attorney.
Yes the question of Rule 704(b) remains, but from what I see of the discussion, good lawyering should pretty much render the rule unnecessary because it would seem to be very counter productive to get into that territory.
A few years ago, I wrote a paper in Judge Easterbrook's Legal Interpretation class on precisely this issue--the paradox of outcome (aggregating each justice's overall disposition) and issue (aggregating each justice's stance on individual issues) voting systems. Splintered plurality opinions in complex cases (see National Pork case from last term) demonstrate how cycling (see public choice theory) can create a seemingly arbitrary result where conflicting minority opinions can produce majority results. It's challenging to feel confident one way or another about which system is "better" (whatever that means). Ultimately, I concluded that outcome voting (the Court's current approach, as moderated by the Marks rule when you have a plurality) was superior because it better safeguards against strategic behavior; in a pure issue voting system, a justice might be tempted to strategically vote dishonestly on one issue if he or she cares deeply about the overall outcome. Also, we generally don't expect alignment of reasoning (as required in issue voting systems) in virtually any other voting system, such as juries voting to acquit or convict, congressmen voting up or down on legislation, or friends trying to vote on which restaurant to visit for dinner. In those situations, the overall disposition of each voter--as determined by each person's distinct reasoning--is what matters the most, and I'm not so sure why the legal system is any different. Outcome voting also solves (or at least mitigates) the challenge you pose in this post: issues can be broken into sub-issues and sub-sub-issues (into infinity), and if we prioritize alignment of reasoning the most, why stop at the first layer of issues? A final thought I've been exploring more recently is whether focusing too excessively on the abstract can undermine the Supreme Court's fundamental duty to resolve cases and controversies of disputing parties. Put differently, by turning too far away from disputing parties and focusing only on abstract coherence (a sort of choose your own adventure thought experiment) of reasoning and not the overall disposition, isn't the Court undermining the justice owed to the disputing parties right before them? I've never heard anyone raise this point before, so it's likely wrong or misconceived, but I haven't heard many satisfying answers when I raise point this in legal circles. Thanks for the thought-provoking post.
Are juries supposed to be better at evaluating the evidence? I thought the jury trial was supposed to be a defense against tyranny not epistemically superior (and other countries experience skipping juries seems to back this up as does my experience on them).
Absolutely fascinating! In a short amount of time, this is already becoming one of my favorite Substacks.
My take on the matter: Even though I think the officer's testimony is sort of bullshit and that Diaz should not have been convicted if that was indeed the key factor motivating the jury, I don't believe that the testimony should be barred on basis of 704(b). To me, what distinguishes this case from Trump v. Anderson case is simple, and how to resolve the tension between arbitrary distinction and atextual expansion is about the spirit of the law:
In Trump v Anderson, I cannot think of a single reason why the Fourteenth Amendment would've been written to exclude presidents. That this is even a discussion feels like a simple oversight, and therefore, the pro-disqualification side should win.
With 704(b), however, there's a clear benefit to be had from experts providing testimony regarding general probabilities. This benefit may be marginal, and it may have its other drawbacks (e.g., by being too persuasive), but saying something like "In 99.99% of cases, drug mules are knowing participants" imparts information. (It's especially clear when you imagine a different percentage--what if drug mules were knowing participants only in 75% of cases?) This is a statistic, in some ways a fact, which puts it in contrast to psychologists' speculations about a person's interiority. (I say "in some ways" a fact, because statistics can be so easily and so often twisted or misunderstood by lack of context or lack of Bayesian reasoning.)
What I suspect we need is new rules or legislation around the usage of statistics in testimony, and that would make the 704(b) issue no longer matter.
I’m quite dubious of the AI recommendation. I thought the article was interesting for showing how deep the rabbit hole goes, even for a simple question.
It seems to me that the difficulty comes from wanting consistency, because there are so many things that a ruling could be consistent with in so many ways. Considered as a standalone policy question, it seems simpler: how much evidence should we require for punishing someone as a drug mule? Is finding a large amount of fentanyl in the car enough evidence, or is more needed to avoid punishing unwitting drug mules? Even if that possibility is rare, it should be considered. Perhaps punishment should be less without having further evidence of intent?
A legislature considering the policy question should probably take into account how drug smuggling currently works, with better evidence than one expert’s opinion. And then, also take into account how criminals respond to incentives, and that’s going to be a guess. Tactics change.
It seems like the court system isn’t a great place to have this policy debate, because everything becomes a consistency argument, including consistency with rules that are quite far removed from how best to fight drug trafficking without punishing innocent people.
As a non-lawyer (who teaches psychology to pre-law students), I want to say I really enjoyed the Juror Ids and Egos post, as it gave great context to our class discussions on how judges have no idea how jurors evaluate evidence. I'll have to add this to the reading list too!
SCOTUS will of course affirm. The whole concept of experts testifying about the MOs of drug traffickers is absurd and outrageous. Who is the defendant supposed to cross examine—some opinion-haver who knows nothing of this defendant or the actual people who secreted the drugs?
I don’t have a law background, but as an American it seems absurd that we would ever accept evidence of the form “People like x usually also are y”, because inherently there is always reasonable doubt. Statistical arguments should never be admissible in court, only direct fact based ones. Similarly, since psychology tells us that memories are often fallible, we should never accept witness testimony except in the most blatant cases (“I saw her fire the gun and then get caught by the officer, without losing sight of her”). There is a huge degree of doubt introduced by these types of arguments, and we shouldn’t let prosecutors get away with providing any doubt.
Really never? So you can basically never sue tobacco or asbestos companies because the proof of causation is entirely statistical? Even DNA evidence is ultimately based on a statistical claim about inadvertant matches.
A well-defined appropriate statistical result is, imo, far better than most trial testimony. It's just that statistics is hard and most people don't understand the subtleties.
Really our common sense is also a kind of statistical argument as well.
Hmm, I guess I underdefined "statistical argument". I'm fine with group statistical arguments - saying "there's a 50% chance for smoking to cause death, multiplied by 1,000,000 smokers, so smoking killed around 500,000 people, plus or minus some number" - but not individual statistical arguments - "this person smoked, smoking kills 50% of smokers, so smoking killed this person" (or even "smoking kills 98% of smokers, so smoking killed this person"). Statistical arguments are also more fine in civil cases than criminal cases, when there only needs to proven preponderance of the evidence, rather than proof beyond a reasonable doubt.
Perhaps the Supreme Court could define a statistical chance for what "beyond a reasonable doubt" means - does it need a 99% chance? 99.9%? 99.99%? But without a number defining what that cutoff should be, it's easy for a prosecutor to portray a relatively low chance as being essentially certain.
For DNA evidence, I think that the legal system should be more careful about it! There was a recent article about it (https://www.lexology.com/library/detail.aspx?g=2800ffc0-c286-4094-80a5-ad4419908bc0) talking about how prosecutors often incorrectly think that DNA evidence is stronger than the science says that it is.
I think the problem that this issue goes to is: what do you do about evidence that can be absurdly strong (stronger than anything we infer by common sense) but for which most jury members and judges just aren't familiar enough with to understand when it's genuinely strong or a subtle fallacy.
I mean we can't demand that only mathematicians sit on juries. At the same time it seems crazy to say that you can't introduce really irrefutable proof because someone might claim to have it when they don't.
It might be fine if it wasn't the case that the defense is rarely able to hire the expert to evaluate it...maybe allow it in criminal cases only if the government pays for a decent defense statistics expert to throughly review the claims.
But if you want a wrongful death judgement the law demands you prove causation. For good reason, you can't argue that there is a 1% chance that roundup killed your spouse and get 1% of the damages. So those cases kinda have to take statistical evidence and determine that it exceeds some sufficient threshold.
Sure, beyond a reasonable doubt is a higher standard but now that you have the principle are you really going to say there is no threshold?
"You claim not to have had any contact with the deceased at all but every week you play the lotto with random numbers and we found a notebook with her name on it with a page titled lotto numbers and each week those numbers exactly match the tickets we found in your drawer"
Work it out and the chance that it's a coincidence is far far less than the absurd theory someone who just happened to look exactly like you drove up in the same model car you drive and shot your girlfriend in front of witnesses.
We may not know exactly where that threshold is legally but that doesn't mean there aren't clear cases. As the above illustrates in some sense all testimony is a stat judgement (all the witnesses didn't just happen to have a seizure that caused them all to hallucinate the same thing).
Re: DNA evidence they should be more careful but I thought it's now more an issue of transfer since everyone moved to longer profiles after UK false positive...but maybe still damaged profiles are an issue.
As a long-lapsed (reformed?) lawyer with a district court background, that was thoroughly enjoyable.