The tragedy
Rebecca Riley, age 4, died in the throes of pneumonia, while very heavily medicated on Depakote and Clonidine, intended to treat ADHD and bipolar disorder. Her parents, Carolyn and Michael, are on trial for Rebecca's murder (Read about the trial here). According to prosecutors, Carolyn and Michael routinely lied to doctors in an effort to get all their children prescribed strong drugs, eventually finding a Boston psychiatrist willing to believe them and hand out ever-stronger doses. Prosecutors claim that the Rileys cared only about making their children easy to manage, regardless of any adverse health consequences, and collecting federal disability benefits. Eventually, after being given extremely high dosages of these powerful drugs, even by adult patient standards, Rebecca died in her parents' home.
When a tragedy like this strikes, it is quite natural for ordinary people to want to assign blame. Someone must have been responsible and that person should be held accountable. Why is there such a palpable need to assign blame? It stems from several reinforcing psychological phenomena.
The human need for answers and accountability
The first is a natural aversion to reminders of one's own mortality. We don't like to feel vulnerable. Therefore, when bad things -- deadly things -- happen to others, our brains automatically generate reasons why such threats aren't dangerous to us. A standard response is to generate distinctions between the victim's circumstances and our own. Some distinctions are circumstantial, while others are directed at choices made by the victim or some other responsible party.
A second psychological response to such a tragedy is to shrink back from the randomness of a bad event. We don't like to think that we are not in control of our own lives. We like to think that our own actions and choices will insure our own well-being. Therefore, people tend to overestimate the control that someone else could have exercised over a difficult situation. This is because any bystander would like to believe that, had she been in the same situation, she would have been able to stop the tragedy from occurring.
Finally, as I have written about on a number of occasions, hindsight bias is always at play when rare events take place. Ordinary people have a great deal of trouble processing the true chance of very unlikely events. The numbers just get too small for the brain to easily process. (What does a 1-in-500,000 chance really look like?). Also, the cognitive availability of an event (after all, the event is the focus of the trial) makes it seem more likely to have occurred. This tendency to overestimate the likelihood of an event also results in people overestimating the events predictability and preventability. An odd second-order effect is that the more peculiar the circumstances, the more likely people are to assume that a tragedy could have been averted.
Jurors are not experts in risk assessment. They typically don't have degrees in statistics or bioinformatics. They are ordinary folks, tasked with processing some very foreign circumstances. As such, they will be subject to the kinds of cognitive tendencies outlined above. The Rebecca Riley death is a very strange story. The loss of a young child is every parent's worst nightmare. The world of pediatric psychiatry seems very alien to all of the jurors. All of these factors will combine to make the jurors very eager to find someone to blame for this horrible tragedy. Once they assign blame, they can go back to believing that such a thing could never happen to them.
What should the defense team do?
This is the environment in which Carolyn and Michael Riley are being tried. One defense strategy might be to portray this death to the jury as an unfortunate accident. For the reasons I outline above, I think this will be an extremely tough sell. A better strategy would be to try to deflect blame onto others. Let the jurors have their culprit, but try to convince at least some of them that the culprit is someone other than the defendant.
The defense team took a sensible first step in this direction by requesting separate trials for the two parents. This allows each to deflect responsibility to the other. The key for Carolyn's legal team is to get at least some on the jury to assign more responsibility to her husband than to her. Frankly, based on what we have heard so far, such a tactic would seem more promising for Michael's defense than for Carolyn's.
The second likely candidate for deflected blame is the psychiatrist who prescribed the medication. Dr. Kayoko Kufuji has now testified in Carolyn's trial. While she came across as detached and somewhat clueless, which points to her own negligence, the prosecution did a very good job of showing how Dr. Kufuji relied very heavily on Carolyn Riley's own characterizations of her children, when making her diagnoses. As such, Kufuji's failures seem largely the result of Carolyn Riley's dishonesty and manipulation.
The third candidate for deflected blame, and the one I think is most likely to garner some sympathy with jurors, is Carolyn Riley's own mental state. The prosecutor is trying to paint a picture of a calculating, manipulative mother who happily endangered her children to keep them docile and to collect federal disability checks. The defense might just gain some traction by telling the jury that she was mentally unbalanced. There are official conditions, like Munchausen-by-proxy, where parents imagine or invent illnesses in their children to fulfill a pathological need for attention. Alternatively, the defense could attribute her extreme behavior to the abusive treatment by her husband. Michael Riley has been banned from a prior residence due to violent behavior and Carolyn Riley once took out a restraining order against her husband, ostensibly to protect her children. Under such a scenario, the defense can contend that the system let Carolyn down, enabling behavior that was not only self-destructive, but also endangered the Riley children.
Will it work?
Jurors are generally skeptical of victimization arguments like the one I outline above, but it seems the best strategy in a case like this. There is a documented history of spousal abuse. Many authority figures who interacted with Carolyn and her children failed to take official action. Remember that only one juror needs to be convinced that Carolyn Riley wasn't completely responsible for her own actions to avoid a murder conviction.
The defense strategy needs to be focused on getting Carolyn's sanity into the discussion in the jury room. They need to open the door for those who might be inclined to take pity on her. I rather doubt that the jury will initially be unanimous in its evaluation of her culpability. Arguments will be heated. Tears will be shed. Playing up the defendant's mental instability might not keep her out of jail, but I could see a conviction on a lesser included offense, such as involuntary manslaughter. Given what has transpired in court so far, that would probably be considered a victory for the defense.
Recent Jury Box Blog Entries
Thursday, January 28, 2010
Tuesday, January 26, 2010
Supreme Court absolutely unclear on Constitutionality of absolute disparity test
Another Black man convicted by an all-white jury
Last week, the US Supreme Court heard oral arguments in the case of Berghuis v. Smith. Smith, who had been convicted in Kent County, Michigan of second-degree murder, objected to the pool from which his jury had been chosen. Of the 60 to 100 potential jurors, at most 3 were African American, despite the relevant county having 8% African American population. Smith objected to a local practice of assigning prospective jurors to courthouses near their homes, rather than randomly assigning them within the county. He argued that a trial in a rural courthouse would almost certainly result in a jury pool lacking an appropriate proportion of African Americans, since most of them lived in or near Grand Rapids. Smith also objected to the court's liberal dismissal of jurors for childcare or transportation hardship reasons, which, he argued, disproportionately applied to African American jurors.
The specific practices identified by Smith are important for the Court's evaluation of "systematic exclusion" of minority jurors. These practices, however, are not the focus of this entry. Rather, I am more interested in the Court's revisiting of an old, established and logically bankrupt standard for measuring the representativeness of a jury pool: the absolute disparity test.
The Twisted Logic of the Absolute Disparity Test
Since Swain v. Alabama, the Supreme Court has endorsed a particular formula for determining whether a jury pool is sufficiently representative. Calculate the baseline percentage of a minority group in the county's population. Subtract from this the percentage of minority representatives in jury pools (averaged over some period of time). This is the measure of "absolute disparity." Typically, if this absolute disparity is less than 10%, the jury selection scheme, on its face, does not violate the 6th Amendment's "fair cross-section" requirement.
Smith points out in his brief that it is not possible for a jury selection system to violate the provision unless the minority population of the county is at least 10%. Los Angeles County, for instance, only has a 9.45% black population. As such, under the absolute disparity test, the complete absence of any African Americans on any of LA's jury panels would still be Constitutionally acceptable.
Consider the following county level map of the United States, color-coded for African American population:
Only the counties that are orange or red could ever run afoul of the 6th Amendment cross-section requirement, regardless of their treatment of potential African American jurors. (Of course, any jurisdiction caught with a smoking gun policy of discriminating against minorities in jury selection would still run into 14th Amendment difficulties.) The rest of the country would seem to be free to completely ignore whether minorities ever get called for jury duty.
A True Measure of Representativeness
The alternative to the absolute disparity test is, unsurprisingly, the comparative disparity test. As with the absolute test, the first step is to calculate the percentage of the county that is African American. The next step, however, is to calculate the percentage of African Americans on jury panels as a proportion of the percentage in the general population. For instance, if a county is 8% black and only 3% of people on jury panels are black, the comparative disparity measure is 5/8 or 62.5%. The comparative disparity test is capable of calculating equivalently underrepresentation in both heavily minority counties and those with relatively few minorities.
Any statistician will tell you that a 5% variation in black representation might be caused by any sort of sampling error in a population that is 60% black, but such an absolute variation in a population that is only 10% black is almost certainly the result of systematic forces. The absolute disparity metric can mask what is really going on while the comparative one is more likely to alert interested parties when systemic underrepresentation is taking place.
Justice Scalia is flummoxed by the binomial distribution
After the case went back and forth in the Michigan state courts, Smith brought his case to Federal court. The Sixth Circuit Court of Appeals reasoned that the comparative disparity measure was more appropriately applied in cases like this one, where minority representation in the general population is relatively low.
In oral arguments at the Supreme Court, Justice Breyer seemed to understand the fundamental flaw in the previously controlling formula. He tried to enlighten his brethren by citing an example of an urn with two different colored balls in it. If there were 8% red balls, what are the chances that one would randomly only choose 3 red balls out of 100? This use of the binomial theorem seemed to annoy Scalia, who was unable (or unwilling) to conceive of the problem on this abstract level. He quipped, "But we don't have an urn, do we?"
With logic firmly shoved onto the back burner, most of the other justices seemed content to grill the litigants about the particular procedures (assignment to local courthouses and liberal hardship excuses) highlighted in respondent's brief. Justices Kennedy and Stevens did press Eric Restuccia, the Michigan Solicitor General, to explain when one formula should be used over another. He declined on the grounds that the only question before the court was whether the trial court's interpretation was inherently unreasonable.
Will common sense prevail?
It so rarely does. In this case, however, I don't think that supporters of the comparative disparity test need despair. I expect that the Court will find some way to decide this case on narrow, procedural grounds, upholding the general deference principal articulated in the AEDPA. This does not preclude, however, the justices from speaking to the issue of the correct test in dicta. If enough of the court's members come to appreciate the perverse results that emanate from application of the absolute disparity metric, we might just see a sea change in representativeness analysis for future cases.
Last week, the US Supreme Court heard oral arguments in the case of Berghuis v. Smith. Smith, who had been convicted in Kent County, Michigan of second-degree murder, objected to the pool from which his jury had been chosen. Of the 60 to 100 potential jurors, at most 3 were African American, despite the relevant county having 8% African American population. Smith objected to a local practice of assigning prospective jurors to courthouses near their homes, rather than randomly assigning them within the county. He argued that a trial in a rural courthouse would almost certainly result in a jury pool lacking an appropriate proportion of African Americans, since most of them lived in or near Grand Rapids. Smith also objected to the court's liberal dismissal of jurors for childcare or transportation hardship reasons, which, he argued, disproportionately applied to African American jurors.
The specific practices identified by Smith are important for the Court's evaluation of "systematic exclusion" of minority jurors. These practices, however, are not the focus of this entry. Rather, I am more interested in the Court's revisiting of an old, established and logically bankrupt standard for measuring the representativeness of a jury pool: the absolute disparity test.
The Twisted Logic of the Absolute Disparity Test
Since Swain v. Alabama, the Supreme Court has endorsed a particular formula for determining whether a jury pool is sufficiently representative. Calculate the baseline percentage of a minority group in the county's population. Subtract from this the percentage of minority representatives in jury pools (averaged over some period of time). This is the measure of "absolute disparity." Typically, if this absolute disparity is less than 10%, the jury selection scheme, on its face, does not violate the 6th Amendment's "fair cross-section" requirement.
Smith points out in his brief that it is not possible for a jury selection system to violate the provision unless the minority population of the county is at least 10%. Los Angeles County, for instance, only has a 9.45% black population. As such, under the absolute disparity test, the complete absence of any African Americans on any of LA's jury panels would still be Constitutionally acceptable.
Consider the following county level map of the United States, color-coded for African American population:
Only the counties that are orange or red could ever run afoul of the 6th Amendment cross-section requirement, regardless of their treatment of potential African American jurors. (Of course, any jurisdiction caught with a smoking gun policy of discriminating against minorities in jury selection would still run into 14th Amendment difficulties.) The rest of the country would seem to be free to completely ignore whether minorities ever get called for jury duty.
A True Measure of Representativeness
The alternative to the absolute disparity test is, unsurprisingly, the comparative disparity test. As with the absolute test, the first step is to calculate the percentage of the county that is African American. The next step, however, is to calculate the percentage of African Americans on jury panels as a proportion of the percentage in the general population. For instance, if a county is 8% black and only 3% of people on jury panels are black, the comparative disparity measure is 5/8 or 62.5%. The comparative disparity test is capable of calculating equivalently underrepresentation in both heavily minority counties and those with relatively few minorities.
Any statistician will tell you that a 5% variation in black representation might be caused by any sort of sampling error in a population that is 60% black, but such an absolute variation in a population that is only 10% black is almost certainly the result of systematic forces. The absolute disparity metric can mask what is really going on while the comparative one is more likely to alert interested parties when systemic underrepresentation is taking place.
Justice Scalia is flummoxed by the binomial distribution
After the case went back and forth in the Michigan state courts, Smith brought his case to Federal court. The Sixth Circuit Court of Appeals reasoned that the comparative disparity measure was more appropriately applied in cases like this one, where minority representation in the general population is relatively low.
In oral arguments at the Supreme Court, Justice Breyer seemed to understand the fundamental flaw in the previously controlling formula. He tried to enlighten his brethren by citing an example of an urn with two different colored balls in it. If there were 8% red balls, what are the chances that one would randomly only choose 3 red balls out of 100? This use of the binomial theorem seemed to annoy Scalia, who was unable (or unwilling) to conceive of the problem on this abstract level. He quipped, "But we don't have an urn, do we?"
With logic firmly shoved onto the back burner, most of the other justices seemed content to grill the litigants about the particular procedures (assignment to local courthouses and liberal hardship excuses) highlighted in respondent's brief. Justices Kennedy and Stevens did press Eric Restuccia, the Michigan Solicitor General, to explain when one formula should be used over another. He declined on the grounds that the only question before the court was whether the trial court's interpretation was inherently unreasonable.
Will common sense prevail?
It so rarely does. In this case, however, I don't think that supporters of the comparative disparity test need despair. I expect that the Court will find some way to decide this case on narrow, procedural grounds, upholding the general deference principal articulated in the AEDPA. This does not preclude, however, the justices from speaking to the issue of the correct test in dicta. If enough of the court's members come to appreciate the perverse results that emanate from application of the absolute disparity metric, we might just see a sea change in representativeness analysis for future cases.
Thursday, January 07, 2010
Murder Trial to test public attitudes towards mental illness
Preschooler diagnosed with ADHD dies from overmedication: Parents on Trial for Murder
Rebecca Riley was diagnosed with ADHD and a bi-polar disorder before her third birthday. Her treatment was supervised by a respected pediatric psychologist, who prescribed two powerful medications, normally reserved for adults. While not approved for such use by the FDA, such "off label" uses are at the professional discretion of the treating physician, and are not uncommon.
Just over a year later, Rebecca Riley died.
The Massachusetts Medical Examiner concluded that her death was caused by an overdose of her medicine. Her parents, Michael and Carolyn Riley, on trial for her murder, claim that she died from pneumonia contracted shortly before her death. A grand jury refused to indict the girl's physician, concluding that the prescribed dosage was not to blame. Rather, the grand jury indicted the parents for murder on the theory that they intentionally overmedicated their daughter to make her easier to manage.
Read about the trial here.
There is some incriminating evidence that the Rileys will have to counter during their trial. School officials, including the school nurse, reported that the girl was often listless and non-responsive in school, sometimes requiring assistance just to get on or off the school bus. In addition, according to the girl's doctor, Mrs. Riley often requested additional refills of her daughter's medicine, claiming that she had lost or damaged bottles of pills. Finally, the Rileys' other two children have also been diagnosed with similar conditions and are being treated in a similarly aggressive way.
Are all these children really mentally ill?
Without a "smoking gun," per se, the outcome of this case will depend, to a great deal, on public perceptions of pediatric mental illness in the modern era. There are clearly countervailing trends and it remains to be seen how they will balance out.
On the one hand, psychiatry (with a big assist from neuroscience) has come a long way in identifying the physiological and neurological causes (or at least traces) of many previously undiagnosed (or misdiagnosed) conditions. We no longer throw women into insane asylums for "bad humors" or "hysteria." Most members of the public believe that depression actually exists and has a neurological foundation. People now appreciate the hereditary influences on alcoholism and other forms of "abhorrent" behavior. Americans generally recognize that soldiers and witnesses to war really do express post traumatic stress disorders. Mental illness is no longer a taboo subject the way it was even 50 years ago.
On the other hand, the public is clearly skeptical of the increasing propensity of mental health professionals to assign a syndrome name to virtually every form of unusual or undesirable behavior. Most current adults were raised during a time when behavioral problems among students were handled behaviorally, rather than psychologically. Children were expected -- required -- to behave themselves in school and at home. There were certainly allowances made for kids who were fidgety or had difficulty paying attention, but children were generally held accountable for their own actions. The primary objection to the current climate of diagnosing every other kid with some kind of disorder or syndrome is that we are raising a generation of people who won't know how to be responsible for their own decisions and actions. By making excuses for our kids, we are raising a nation of excuse-makers.
Modern pediatric psychiatry and parenting on trial
With these countervailing trends in play, how will jurors in this case perceive of the actions of Rebecca Riley's parents? Some may be inclined to defer to the girl's psychiatrist, excusing the parents for doing the same. They gave her these drugs because their doctor said it was OK. The doctor must have seen Rebecca on a regular basis. If she didn't seem concerned, then the parents had no way of knowing that Rebecca was in any kind of danger.
Other jurors will be skeptical of the parents' motives. A parent can get some doctor to diagnose a kid with some kind of disorder if they push hard enough. These folks obviously wanted to medicate their daughter to make their own lives easier. Why didn't they focus on trying to be better parents?
The wild card in this debate might just be the Rileys' handling of their other children. Jurors are notoriously bad at understanding and processing arguments based on probabilities. Unfortunately for the lawyers in this case, conveying the implications of the diagnoses of Rebecca's siblings requires the jurors to wrestle with such issues.
Consider the numbers: It is estimated that roughly 1 out of every 9 American children has some level of diagnosable ADHD. That is about 11%. One might then conclude that the chance of all three Riley children having ADHD is 0.11 cubed, or 0.0013 -- roughly one in a thousand. (Apparently only about 1/3 of children with ADHD receives the treatment she requires. As such, public perception would be that only about 4% of children have ADHD.) By such logic, it is extremely unlikely that the Riley kids got similarly diagnosed purely by chance. With such astronomical odds against it, the parents must really have been pushing doctors to diagnose ADHD.
Such logic is spurious, however, because it assumes that the incidence of ADHD among siblings are independent events. In truth, due to the shared genetics and physiology of siblings, having a brother or sister with ADHD substantially increases the chance of a child having the disorder.
This leaves the jurors in a tricky bind. Everything turns on the reliability of the doctor's diagnostic techniques. If her diagnoses of Rebecca's siblings were correct, her diagnosis of Rebecca almost certainly was, too. On the other hand, if her methods were suspect, the likelihood that she properly diagnosed Rebecca's condition, in particular, drops dramatically.
How to explain this to jurors
I have written in other blog entries about the "perils of probability." I also regularly discuss this issue with attorneys to whom I give presentations. It is very difficult to teach enough probability theory to jurors that they actually "get it." Don't expect them to be able to replicate the math. On the other hand, it is possible to provide them with enough insight to appreciate the nature of the results. My advice: Use visual aids to convey comparisons between probabilities. Analogize to decisions-under-risk with which jurors might be familiar. Make sure that your expert witnesses are excellent teachers. Jurors perceive as more reliable those witnesses who are seen as "helpful."
Regardless of the exact presentation strategies a litigator employs, she would always be wise to test its efficacy in advance. You might think your expert's explanation is crystal clear, but you can't be sure until you present it to a group of ordinary people and find out what they think. If your case turns on the "perils of probability," as the Riley case seems to, some sort of pretrial jury study (focus group research) is absolutely essential.
Rebecca Riley was diagnosed with ADHD and a bi-polar disorder before her third birthday. Her treatment was supervised by a respected pediatric psychologist, who prescribed two powerful medications, normally reserved for adults. While not approved for such use by the FDA, such "off label" uses are at the professional discretion of the treating physician, and are not uncommon.
Just over a year later, Rebecca Riley died.
The Massachusetts Medical Examiner concluded that her death was caused by an overdose of her medicine. Her parents, Michael and Carolyn Riley, on trial for her murder, claim that she died from pneumonia contracted shortly before her death. A grand jury refused to indict the girl's physician, concluding that the prescribed dosage was not to blame. Rather, the grand jury indicted the parents for murder on the theory that they intentionally overmedicated their daughter to make her easier to manage.
Read about the trial here.
There is some incriminating evidence that the Rileys will have to counter during their trial. School officials, including the school nurse, reported that the girl was often listless and non-responsive in school, sometimes requiring assistance just to get on or off the school bus. In addition, according to the girl's doctor, Mrs. Riley often requested additional refills of her daughter's medicine, claiming that she had lost or damaged bottles of pills. Finally, the Rileys' other two children have also been diagnosed with similar conditions and are being treated in a similarly aggressive way.
Are all these children really mentally ill?
Without a "smoking gun," per se, the outcome of this case will depend, to a great deal, on public perceptions of pediatric mental illness in the modern era. There are clearly countervailing trends and it remains to be seen how they will balance out.
On the one hand, psychiatry (with a big assist from neuroscience) has come a long way in identifying the physiological and neurological causes (or at least traces) of many previously undiagnosed (or misdiagnosed) conditions. We no longer throw women into insane asylums for "bad humors" or "hysteria." Most members of the public believe that depression actually exists and has a neurological foundation. People now appreciate the hereditary influences on alcoholism and other forms of "abhorrent" behavior. Americans generally recognize that soldiers and witnesses to war really do express post traumatic stress disorders. Mental illness is no longer a taboo subject the way it was even 50 years ago.
On the other hand, the public is clearly skeptical of the increasing propensity of mental health professionals to assign a syndrome name to virtually every form of unusual or undesirable behavior. Most current adults were raised during a time when behavioral problems among students were handled behaviorally, rather than psychologically. Children were expected -- required -- to behave themselves in school and at home. There were certainly allowances made for kids who were fidgety or had difficulty paying attention, but children were generally held accountable for their own actions. The primary objection to the current climate of diagnosing every other kid with some kind of disorder or syndrome is that we are raising a generation of people who won't know how to be responsible for their own decisions and actions. By making excuses for our kids, we are raising a nation of excuse-makers.
Modern pediatric psychiatry and parenting on trial
With these countervailing trends in play, how will jurors in this case perceive of the actions of Rebecca Riley's parents? Some may be inclined to defer to the girl's psychiatrist, excusing the parents for doing the same. They gave her these drugs because their doctor said it was OK. The doctor must have seen Rebecca on a regular basis. If she didn't seem concerned, then the parents had no way of knowing that Rebecca was in any kind of danger.
Other jurors will be skeptical of the parents' motives. A parent can get some doctor to diagnose a kid with some kind of disorder if they push hard enough. These folks obviously wanted to medicate their daughter to make their own lives easier. Why didn't they focus on trying to be better parents?
The wild card in this debate might just be the Rileys' handling of their other children. Jurors are notoriously bad at understanding and processing arguments based on probabilities. Unfortunately for the lawyers in this case, conveying the implications of the diagnoses of Rebecca's siblings requires the jurors to wrestle with such issues.
Consider the numbers: It is estimated that roughly 1 out of every 9 American children has some level of diagnosable ADHD. That is about 11%. One might then conclude that the chance of all three Riley children having ADHD is 0.11 cubed, or 0.0013 -- roughly one in a thousand. (Apparently only about 1/3 of children with ADHD receives the treatment she requires. As such, public perception would be that only about 4% of children have ADHD.) By such logic, it is extremely unlikely that the Riley kids got similarly diagnosed purely by chance. With such astronomical odds against it, the parents must really have been pushing doctors to diagnose ADHD.
Such logic is spurious, however, because it assumes that the incidence of ADHD among siblings are independent events. In truth, due to the shared genetics and physiology of siblings, having a brother or sister with ADHD substantially increases the chance of a child having the disorder.
When one child in a family has ADHD, a sibling will also have the disorder 20% to 25% of the time, says geneticist Susan Smalley, PhD, co-director of the Center for Neurobehavioral Genetics at the David Geffen School of Medicine at UCLA (www.adhd.ucla.edu). About 15% to 40% of children with ADHD will have at least one parent with the same condition.By this logic, the fact that both of Rebecca's siblings have been diagnosed with ADHD makes it substantially more likely that Rebecca was correctly diagnosed with ADHD. If having one sibling with ADHD would increase the likelihood of Rebecca having it by almost three times, having two afflicted siblings would likely increase the chances five-fold.
This leaves the jurors in a tricky bind. Everything turns on the reliability of the doctor's diagnostic techniques. If her diagnoses of Rebecca's siblings were correct, her diagnosis of Rebecca almost certainly was, too. On the other hand, if her methods were suspect, the likelihood that she properly diagnosed Rebecca's condition, in particular, drops dramatically.
How to explain this to jurors
I have written in other blog entries about the "perils of probability." I also regularly discuss this issue with attorneys to whom I give presentations. It is very difficult to teach enough probability theory to jurors that they actually "get it." Don't expect them to be able to replicate the math. On the other hand, it is possible to provide them with enough insight to appreciate the nature of the results. My advice: Use visual aids to convey comparisons between probabilities. Analogize to decisions-under-risk with which jurors might be familiar. Make sure that your expert witnesses are excellent teachers. Jurors perceive as more reliable those witnesses who are seen as "helpful."
Regardless of the exact presentation strategies a litigator employs, she would always be wise to test its efficacy in advance. You might think your expert's explanation is crystal clear, but you can't be sure until you present it to a group of ordinary people and find out what they think. If your case turns on the "perils of probability," as the Riley case seems to, some sort of pretrial jury study (focus group research) is absolutely essential.
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