Courts Refusing to Apply Federal Rule of Evidence 702:

Federal Rule of Evidence 702 was amended in 2000 to provide that expert testimony is admissible only if:(1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case. This rule is both a codification, and to some extent an elaboration, on the so-called "Daubert trilogy" of Supreme Court cases. It's an elaboration because, for example, the Joiner decision stated that courts MAY exclude testimony if an expert witness has taken a potentially reliable principle or methodology, but not applied it reliably to the facts at hand; Rule 702 states that the court MUST do so.

Nevertheless, many federal district courts are simply ignoring or merely paying lip service to Rule 702, and relying on pre-2000 circuit court precedent. A particularly egregious example is Riley v. Target Corp., 2006 WL 1028773, slip op. (E.D. Ark. Apr. 13, 2006). No need to bore readers with the facts of the case. Target challenged the plaintiffs' physician's "differential diagnosis" (which was actually a differential etiology) under Rule 702.

The court found that the methodology of differential diagnosis is a generally reliable one, and then added that any weaknesses in the expert's opinions go to the weight of his testimony, not its admissibility. The court then cited a 1995 (!) circuit court case for the proposition that "[f]aults in an expert's use of differential etiology as a methodology or lack of textual authority for his opinion go to the weight, not the admissibility, of his testimony".

Note that the court not only relied on a pre-2000 precedent that directly contradicts the text of Rule 702, but relied on a pre-Joiner (1997) case! [UPDATE: Even worse, I just noticed, the court quoted a 1995 case for the proposition thhat "[o]nly if an expert's opinion is 'so fundamentally unsupported that it can offer no assistance to the jury' must such testimony be excluded." This was clearly wrong as of 1995, much less now, and thus not surprisingly that case itself, as the court noted, was quoting a 1988, pre-Daubert case! This judge has apparently slept through the last thirteen years of expert evidence jurisprudence.] This case is one of many examples of a court relying on stray dicta from cases that are no longer good law, and paying mere lip service, at best, to the text of Rule 702.

So note to federal district court judges, and their clerks: you shouldn't be relying on any precedent on expert evidence from before 2000, because those precedents relied on a different version of Rule 702, not to mention that many of them were decided before Kumho Tire (1999) and Joiner (which are themselves less strict than amended Rule 702). If you feel the need to do so anyway, the holding needs to be checked against the text of amended Rule 702. If the precedent conflicts with the rule, the rule quite obviously trumps the precedent.

UPDATE: There's nothing inherently wrong with citing pre-2000 precedents, so long as they are consistent with amended Rule 702. But many courts seem unable and unwilling to distinguish precedents that are consistent with Rule 702 and ones that are not. Moreover, the starting point for analysis should be the text of Rule 702, not a circuit court's interpretation of old 702 from 1998. I should add that courts should be cautious about relying even on post-2000 precedents, because many of these themselves ignore the text of 702 and instead cite pre-2000 precedents.

Related Posts (on one page):

  1. Blogging Break:
  2. More on FRE 702:
  3. Courts Refusing to Apply Federal Rule of Evidence 702:
ThirdCircuitLawyer (mail):
Interesting post. Did the briefs in the Riley case point out the amended rule? Or did they rely on the old rule? Might just be a case of really bad lawyering.
5.6.2006 10:45am
Guest44 (mail):
Maybe they think Daubert, Kumho, and 702 are impossible to reconcile with 401/402.
5.6.2006 12:19pm
Cornellian (mail):
I would think that the failure to synchronize the dates of decisions with the dates of rule changes and to draw the appropriate inferences from the chronology is probably a pretty common mistake.
5.6.2006 1:22pm
As both an engineer and an attorney, I tend to believe there is a lot more reasonable dispute and subjectivity in what constitutes "reliable" and "scientific" methodology than the legal community (and perhaps society in general) seems to think. There are definitely considerable philosophical components to defining things like science, evidence, and "fact" -- and the law should probably dissect and declare any assumptions/premises (as should scientists), rather than just assuming that whatever standard(s) of peer-review prevailing at the moment are somehow sacrosanct. (Perhaps Congress could conduct hearings and spell out a particular approach establishing some sort of well-defined empiricist premises, ala Francis Bacon?)

The language in the current standard sounds concrete, but can actually be rather elusive and manipulable.
5.6.2006 2:01pm
Joe Jackson:
I have seen a number of cases like this. IMHO, they often come down to whether the judge wants the plaintiff's "evidence" in front of a jury (i.e., whether the judge likes the plaintiff and/or dislikes the defendant), and not the kind of difficulties raised in comments 2 and 3 above.
5.6.2006 2:16pm
Tennessean (mail):
Here, then, is evidence of the great disconnect between most law (i.e., trial and applied law) and the elite world of teaching and appellate law.
5.6.2006 2:29pm
Expert testimony is practically useless if you have anyone on the jury with any common sense. Which I know those type of persons are weeded out. Just watch Court TV and you will soon learn you can buy whatever
"Expert testimony" you want. I personally would take any of this type of "payed for drivel" with a grain of salt. One says what the prosecutor wants the other the defense. It is obvious one or both is lying with the backing of our Judical System such as it is. I was ONCE as expert witness in a child abuse case. The courtroom let out a gasp when they found out I did not accept any payment. Coarse the other witness took 500.00. I will never be a part of such a dastardly corrupt scheme again.
5.6.2006 2:33pm
You mean judges are just doing what they want and not following the law?!? Heavens, no!
5.6.2006 2:36pm
Anderson (mail) (www):
The language in the current standard sounds concrete, but can actually be rather elusive and manipulable.

This is true of every rule in the book ....
5.6.2006 4:14pm
DaveK (mail):
Prof. Bernstein:

This post strikes me as unfair to the Riley court and not a little histrionic.

Reading the whole case, I can't agree that the district court in Riley misapplied the modern Rule 702 or the Daubert line of cases (which, as you point out, the modern rule is largely a codification of, and which thus should not be ignored). It cited both extensively and was explicitly trying to apply them.

The moving party sought to exclude the expert (Dr. Schrantz), in essence, because his conclusion ran contrary to prevailing wisdom as to how fast AVN develops. The court concluded, however, that Dr. Schrantz's methodology was sound: he used a widely-used and accepted methodology, applied reasonably to the (sufficient) facts of the case--in other words, he met all the elements of modern Rule 702.

The court observed, correctly under both modern and pre-Joiner precedent, that its job "is not to determine whether an expert's opinion is correct; it is an expert witness's methodology, rather than his conclusions, that is the primary concern of Rule 702" (quoting Bonner v. ISP Techs., Inc., 259 F.3d 924, 929 (8th Cir. 2001)--post-Joiner, new-Rule 702, binding circuit precedent). If, after applying acceptable methodology in a sound manner, an expert's conclusion runs against the accepted wisdom, this is no reason to exclude the expert. The expert, after all, might turn out to be right; that's how science works. As the district court says, the expert's contrarianism goes to weight--the expert should be prepared to have his conclusions attacked by opposing experts and on cross-examination, and it's for the factfinder to determine whether they stand up.

After making this observation, the court, perhaps incautiously, threw in a pre-Joiner citation. But it's not clear that the result is wrong today, and the citation was for a throwaway quote. Are you arguing that it's per se incorrect to cite pre-2000 precedent in cases regarding expert witnesses? If not, what did the court do wrong here?
5.6.2006 7:46pm
Michael Masinter (mail):
The Advisory Committee Notes accompanying the 2000 amendments to Rule 702 suggest that the amendment codifies rather than modifies the Daubert trilogy.

Note in particular this language:

A review of the caselaw after Daubert shows that the rejection of expert testimony is the exception rather than the rule. Daubert did not work a ''seachange over federal evidence law,'' and ''the trial court's role as gatekeeper is not intended to serve as a replacement for the adversary system.'' United States v. 14.38 Acres of Land Situated in Leflore County, Mississippi, 80 F.3d 1074, 1078 (5th Cir. 1996). As the Court in Daubert stated: ''Vigorous cross-examination, presentation of contrary evidence, and careful instruction on the burden of proof are the traditional and appropriate means of attacking shaky but admissible evidence.'' 509 U.S. at 595. Likewise, this amendment is not intended to provide an excuse for an automatic challenge to the testimony of every expert. See Kumho Tire Co. v. Carmichael, 119 S.Ct. 1167, 1176 (1999) (noting that the trial judge has the discretion ''both to avoid unnecessary 'reliability' proceedings in ordinary cases where the reliability of an expert's methods is properly taken for granted, and to require appropriate proceedings in the less usual or more complex cases where cause for questioning the expert's reliability arises.'').

When a trial court, applying this amendment, rules that an expert's testimony is reliable, this does not necessarily mean that contradictory expert testimony is unreliable. The amendment is broad enough to permit testimony that is the product of competing principles or methods in the same field of expertise. See, e.g., Heller v. Shaw Industries, Inc., 167 F.3d 146, 160 (3d Cir. 1999) (expert testimony cannot be excluded simply because the expert uses one test rather than another, when both tests are accepted in the field and both reach reliable results). As the court stated in In re Paoli R.R. Yard PCB Litigation, 35 F.3d 717, 744 (3d Cir. 1994), proponents ''do not have to demonstrate to the judge by a preponderance of the evidence that the assessments of their experts are correct, they only have to demonstrate by a preponderance of evidence that their opinions are reliable. . . . The evidentiary requirement of reliability is lower than the merits standard of correctness.'' See also Daubert v. Merrell Dow Pharmaceuticals, Inc., 43 F.3d 1311, 1318 (9th Cir. 1995) (scientific experts might be permitted to testify if they could show that the methods they used were also employed by ''a recognized minority of scientists in their field.''); Ruiz-Troche v. Pepsi Cola, 161 F.3d 77, 85 (1st Cir. 1998) (''Daubert neither requires nor empowers trial courts to determine which of several competing scientific theories has the best provenance.'').
5.6.2006 8:16pm
davidbernstein (mail):

The advisory committee notes can say whatever they want, the text of the rule clearly says that a court must, not may, determine whether an expert is applying a reliable methodology in a reliable way. Call this the committee's "interpretation" of Joiner, or call it a new rule that's stricter than Joiner, it's clearly not what Joiner says. Nor does the language you quoted contradict this. (For that matter, 702 is clearly stricter than Kumho, too, as Kumho does NOT require tha an expert has applied the principles and methods reliably to the facts of the case.)

As for DaveK, the "throw in" citation was directly on point, i.e., whether any purported "differential diagnosis" is admissible, as courts often held pre-2000, or whether a court has an obligation to ensure that the particular differential diagnosis was applied reliably to the facts of the cas, as amended Rule 702 requires about as clearly as any rule could ever require anything.
5.6.2006 8:25pm
DaveK (mail):
Prof. Bernstein:

On point or no, I still don't see why you think the court here misapplied modern Rule 702. The court specifically held that the methodology and its application were reliable, and also--again, using a 2001 binding circuit precedent--that that's as far as its job went. The fact that the expert's method let to an anomalous result was, in essence, what the movant was complaining about--but that goes to weight, not admissibility, even under the modern rule and the Daubert line.

The court cited the rule. The court also cited binding precedent that post-dates the rule. I think it correctly applied the rule, and at the very least, it certainly appears to have been making a good-faith effort to try to do so.

How is this an example of "Courts Refusing to Apply Federal Rule of Evidence 702"?
5.7.2006 3:13am
I agree with DaveK. The suggestion that the Riley Court was "simply ignoring Rule 702, and relying on pre-2000 circuit court precedent" is at best highly misleading when you read the actual opinion. As noted by DaveK, the Riley Court actually quoted and applied Rule 702, and actually relied primarily on 8th Circuit cases from 2000 and 2001. It did cite a pre-2000 2d Circuit case for a somewhat dubious proposition, but the decision in the case did not in any notable way depend on that proposition.

Indeed, in substance, the suggestion seems to be that the Riley Court somehow failed to consider whether the expert witness reliably applied the disputed method ("differential diagnosis," which involves eliminating possible causes until the least unlikely cause remains) to the facts of the case. In other words, the suggestion is that the Riley Court overlooked part 3 of the Rule 702 test.

This suggestion, however, appears to "simply ignore" an entire paragraph of the opinion:

"Although Dr. Schrantz did not use the term 'differential diagnosis' in deposition, his explanation of the reasons for his opinion shows that he employed this method. Dr. Schrantz considered numerous factors that can potentially contribute to the development of AVN and, upon considering Riley's medical history and the events leading up to his hip surgery, eliminated everything except Riley's fall as the cause of his AVN. Target's assertion that Dr. Schrantz ignored Riley's previous alcohol and steroid use and the cysts in Riley's hip is baseless. Dr. Schrantz stated that he considered each of these factors and explained why he ruled them out. Dr. Schrantz concedes that he would generally consider the type of injury that Riley sustained in the fall, which involved swelling and contusions but no fracture or dislocation of the hip, unlikely to result in AVN. Dr. Schrantz concluded that the fall caused Riley's AVN, however, because he considered the other potential causal factors even less likely to have caused the disorder. Given Dr. Schrantz's explanation of the factors that he considered and his reasons for eliminating them, the Court cannot say that his reasoning and methodology were so fundamentally flawed as to render his opinion inadmissible."

This paragraph, of course, goes not only to the general reliability of the method, but also the witness's specific application of the method to the facts of the case.

So, I agree with DaveK that there is no apparent departure from the requirements of modern Rule 702 in this case. And frankly, I think the original post virtually counted on people not bothering to look at the actual case to see what happened.
5.7.2006 10:18am
davidbernstein (mail):
As other courts have properly noted, to engage in a proper differntial etiology, it's not enough to rule out other factors, you have to be able to rule in the alleged causal factor. Given that everyone agreed that "the degree of AVN present at the time of Riley's hip replacement surgery would normally have taken 6 to 12 months from the time of onset to develop," yet only 66 days passed between Riley's accident and surgery, and that the plaintiff had several other, medically accepted risk factors for AVN, the expert concluded that Riley's fall at Target caused his AVN because "the other potential causal factors [were] even less likely to have caused the disorder," I don't see how one can say that the "witness has applied the principles and methods reliably to the facts of the case."

More directly to the point, and this may be Target's attorneys' fault, the Court several times interprets Rule 702 in light of Daubert, which is quite backwards, given that Daubert was 1993 and Rule 702 was 2000, and 702 is much stricter than Daubert. The 2001 8th Circuit case cited by the court is itself questionable, because it does not rely on Rule 702, but quoted a 1999, pre-amended 702, Third Circuit case! And I hadn't noticed it originally, but the 1995 case relied up by the court quotes a 1988 case!
5.7.2006 11:03am
davidbernstein (mail):
Oh, and while the court does quote the text of amended Rule 702 early in the opinion, I believe that's the last we actually hear of the actual text of the rule, and instead the judge relies on precedents that predate the rule.
5.7.2006 11:14am
von (mail) (www):
I agree with the commentators above: This post does not accurately report either the reasoning or the rule applied in Riley. I do agree with Professor Bernstein that the Riley Court appears to place inappropriate weight on a 1995 decision. But Bernstein simply misreads and misrepresents the Riley Court's decision by suggesting that the Court ignored modern Rule 702, <i>Daubert</i>, etc.

This post needs to be revised.
5.7.2006 11:25am
Professor Bernstein,

Are you really arguing now that courts shouldn't be citing any pre-2000 Rule 702 cases? Does that actually include Daubert et al themselves? Because I doubt you will find much agreement on that proposition. And in fact it doesn't make sense--the fact that the rule was amended in 2000 does not automatically mean all prior decisions are a nullity. Rather, insofar as they can still be applied in light of the amended rule, they remain valid.

Anyway, you clearly changed your argument in your last post. Before you were arguing that the Riley Court "simply ignored" modern Rule 702. Now, you seem to be arguing that the Riley Court reached the wrong decision on the merits, given the facts of the case. That is obviously a very significant difference (as evidenced by the fact you originally proposed that the facts of the case didn't matter).

And I don't think that is right on the merits, actually. In the 8th Circuit, at least, "The process of differential diagnosis involves 'ruling in' all scientifically plausible causes of the plaintiff's injury, then 'ruling out' the least plausible causes of injury until the most likely cause is identified." Accordingly, a cause need only be "scientifically plausible" in order to be "ruled in".

So, was the injury a "scientifically plausible" cause of the disease? In general, it seems all agree that such an injury can be the cause of the disease in question. But as you note, the specific issue in the case was this: "Dr. Schrantz also concedes that his conclusion that Riley's AVN developed in the relatively short period of time between the fall and the hip replacement runs counter to the medical profession's understanding of AVN's normal progression and that he knows of no literature or published studies showing that such rapid development is possible." So, the issue is whether this cause was still plausible in light of the relatively short time period.

But the Riley Court rightly reasons that the mere fact that such a result would be "novel" and has not yet appeared in the published literature does not mean the expert's methodology and reasoning were unreliable. Indeed, as DaveK pointed out, it is a truism of modern Rule 702 that it is designed in part to make room for conclusions that are contrary to conventional wisdom, as long as the methods and reasoning are sound. And your argument, like Target's argument, does not go to whether the expert was in fact reliably applying the methodology in question. Rather, you are taking issue with some of the expert's conclusions simply because you apparently would reach a different conclusion about the plausibility of this cause.

In short, you are the one trying to apply a Rule 702 that does not exist (by trying to get into the merits of the conclusions). The Riley Court rightly noted that arguments like yours are actually matters for cross-examination and the ultimate fact-finder. And, of course, none of this has much to do with your original, highly misleading, claims about this opinion.
5.7.2006 11:40am
davidbernstein (mail):
I'll grant that "ignores" Rule 702 was too strong. I'll go with "merely pays lip service to," which is how I've edited the post.

There's no inherent problem with citing pre-2000 cases, except that courts don't seem to be capable, or perhaps willing, to separate pre-2000 cases that are consistent with amended 702, with those that are not. Given that, courts should start with the text of 702, which is pretty clear, and look for precedents that rely on that text.

Finally, Medis, all the expert in this case did was arbitrarily state that one implausible (based on the liteature) etiology was more likely than other possible, but also implausible etiologies. On what basis? None, as far as I can tell from the opinion. And saying it's the most likely of known etiologies ("Schrantz concluded that the fall caused Riley's AVN, however, because he considered the other potential causal factors even less likely [again, on what basis? his personal speculation? not good enough under 702] to have caused the disorder") doesn't go very far toward saying it's even more probable than not. (E.g., we have three plausible etiologies mentioned in the opinion: let's say one is 20% likely the cause, one 25%, one 35%, and the rest is "random chance." The fact that the 35% is "most likely," doesn't mean it's the cause by a prepondernace of the evidence.
5.7.2006 12:13pm
davidbernstein (mail):
P.S. It's possible that the doctor's causation opinion woudl meet the standard of amended Rule 702, but not from what's reflected in the opinion, which makes it seem as if the "differential diagnosis" has no underlying reliable or statistical basis, but the court isn't going to question is, because flaws in reliability go to weight, not admissibility, which is wrong.
5.7.2006 12:31pm
enovack (mail) (www):
The issue of 'expert testimony' is at the heart of much of the effort for medical liability reform. We all know that 'experts' can be found to say almost anything. Juries (at least in AZ) do not have the benefit of knowing that, say, 100 experts would support the defense and only 1 supports the plaintiff.
For the benefit of a regular VC reader who is not an attorney, would you mind expanding on this slightly with a practical example of how the 'modified 702' could impact medical liability cases? The comments imply only semantic, not substantive changes.
On a somewhat related topic, is there any ability to, by statute, allow for 'precedent' in the finding of standard of care to be applied to cases? E.g. if in smith v. dr. a, the standard of care was met, so that now in jones v. dr.b, dr. b's attorney can use the earlier case findings to bolster his case.
thank you!
5.7.2006 12:47pm
go vols (mail):

1) Regardless of whatever interpretation of "must" you read into 702, you surely know that the combination of Joiner's "abuse of discretion" standard for appellate review as well as the command that reliability be defined in flexible terms means that judges, essentially, can define reliability how they like. Your admonition that expert testimony must "rule in" general causation before differential diagnosis can take is a popular rule in some circuits, but is certainly not a legal prerequisite for valid and reliabile claims (outside of any circuit that has made that rule). It's arbitrary ad political, just like rulings that the relative risk must be 2.0 in toxic tort cases or the general convention that statistical significance must be at .05. You're reading your own political predispositions regarding approrpriate levels of risk into the law. Again, those might be good arguments, but they're certainly not required by any of the Daubert precedents or by 702, old or new.

2) Your repeated attacks on Daubert as being too lenient in light of the new 702 are odd, given that the only study (that I've read) which systematically addresses the effect of Daubert on federal civil cases found unambigiously that Daubert had tightened the standards for admissibility across the board (Dixon and Gill, 2002). It's fine to crack at a case here or there, but I think if you want to convince people who aren't already inclined to believe that Peter Huber's observations were something more than a string of anecdotes--and still apply today--you'll need to get your hands dirty in some empirical analysis.

3) If there's any area of federal law that needs a good dose of Daubert, it's criminal law. The Chicago Tribune's series on forensic mishaps last year was bloodchilling. Admittedly, broader studies of this field are difficult because of the relatively few amount of acessible admissibity rulings. That said, I don't see how the "must consider" argument could made in civil cases and then not be applied to criminal ones as well. I would find David's arguments more convincing if they were made across the board.
5.7.2006 1:05pm
go vols (mail):
BTW--for a much nastier (and more substantive) rebuttal of David's claim on the amended 702, check out:
5.7.2006 1:09pm
Professor Bernstein,

Again, I can't help noting that you seem to be ignoring large portions of the opinion. The expert's reasoning with respect to the other possible causes was detailed in a prior section describing his testimony. I'll bring that entire section here in order to let others assess whether it is, as you claim, "arbitrary":

"Dr. Schrantz testified in his deposition that AVN may be caused by a number of factors, including traumatic injury, alcoholism, and steroid use. Dr. Schrantz also testified that the degree of AVN present at the time of Riley's hip replacement surgery would normally have taken 6 to 12 months from the time of onset to develop. The time period between Riley's fall and his surgery, however, was only 66 days. Dr. Schrantz further stated that he would not normally expect the type of hip injury sustained by Riley in the fall to cause AVN. After considering all of the medical evidence, however, Schrantz concluded that Riley's AVN was caused by the fall at Target because Schrantz had considered and eliminated other potential causes.

On May 24, 2004, about three and a half months before Riley's fall, he had a CT (computed tomography) scan that showed his right hip. The CT scan showed that Riley had some cystic changes in his hip, and cystic changes are associated with the progression of AVN. Upon reviewing this CT scan, however, Dr. Schrantz concluded that these cysts were not indicative of AVN because Riley's hip did not show any other signs of AVN, and such signs would shown up on the scan if AVN were present. Dr. Schrantz thus concluded that Riley did not have AVN when the CT scan was performed.

Dr. Schrantz considered the possible effects of alcoholism. Riley reported that he formerly had a problem with alcohol abuse, and alcohol can be a causal factor for AVN. Dr. Schrantz eliminated Riley's alcohol abuse as the cause, however, because Riley had stopped drinking about 40 years earlier. Dr. Schrantz stated that normally AVN associated with alcoholism occurs in current alcoholics and that he knows of no research showing that a distant history of alcoholism has any bearing on the development of AVN.

Dr. Schrantz also considered Riley's history of steroid use. Schrantz testified that AVN usually develops due to steroid use when the patient is a chronic steroid user and that there is normally a close time sequence between the steroid use and the AVN. One of Riley's previous physicians had prescribed a form of steroid treatment for Riley in 2003. Dr. Schrantz concluded that this steroid use did not cause Riley's AVN, however, because the dosage was very low and there was a time lapse between the steroid treatment and Riley's development of AVN.

Finally, Dr. Schrantz considered the fact that Riley's medical records showed no problems with his hip before the fall. Riley saw Dr. Kent for other medical problems during the previous month, but reported no pain or other symptoms associated with his hip. Immediately after the fall, however, Riley experienced severe pain in his hip and sought medical treatment for the problem.

Dr. Schrantz concedes that Riley's case is very unusual in that Riley's AVN developed much faster than Dr. Schrantz would have thought possible. In the medical profession, AVN is understood to be a condition that progresses very slowly. After considering all of the above factors, however, Dr. Schrantz concluded that Riley's fall at Target caused the AVN because Riley's medical history showed that it was not a preexisting condition and other potential causes had been eliminated."

Of course, the District Court here is merely summarizing the expert's deposition testimony. If you really want to second-guess the District Court with respect to the sufficiency of the expert's reasoning, you would need to look at the actual deposition transcript.

As an aside, the expert's conclusion does make sense to me. Basically, once you conclude that there was no AVN shortly before the accident, you have two sorts of scenarios with respect to the known causes. One scenario is that the accident caused the AVN in an unusually short time. The other scenario is that one of these other causes first had a long lag period of not causing the AVN, but then suddently caused the AVN in a very rapid fashion. It makes sense to me that the second scenario is considerably less likely than the first, since it includes two anomalies (the long lag and then the rapid development), and not just one (the rapid development).

Anyway, I also think your edit of your original post dramatically changes its meaning. You are now claiming that the Riley Court was only "paying lip service" to modern Rule 702. And your argument to that effect is basically that the Riley Court got its Rule 702 analysis wrong on the merits. That is a far cry from what you originally claimed.

On a more positive note, I do agree that there is a problem with "differential diagnosis" in general. As you observe, one has to consider the possibility of unknown causes (personally, I wouldn't say "random", because I don't think that really captures the nature of residual causal chances). Then again, one can overstate this problem, particularly when one is comparing the possibility of an unknown cause acting in a previously unknown fashion to the possibility of a known cause acting in a previously unknown fashion. In any event, the probability one should assign to residual unknown causes is a factual question, and this problem does not make this methodology per se unreliable.

Of course, I also agree that the ultimate factfinder has to apply the preponderance of the evidence standard, and not simply identify the most likely cause among many. But on the other hand, there is no inherent reason that this methodology could not establish the most likely cause as being above 50% (again, it all depends on various probability assignments in light of the evidence). Moreover, if there is other evidence of cause besides this medical evidence, then the medical evidence alone need not establish cause to the satisfaction of the preponderance standard.

But anyway, once again your general criticism of the methodology of differential diagnosis is going to the merits of the issue. And on that issue, the Riley Court was indeed bound by the 8th Circuit's 2000 and 2001 opinions on the subject. So, your original claim, and even your modified claim, still seem misleading to me. What you are really arguing is just that the 8th Circuit got it wrong on the merits--but that does not prove that they ignored or merely paid lip service to the rule, and certainly doesn't show that the Riley Court did so.
5.7.2006 2:07pm
davidbernstein (mail):
Medis, one quick point: I'm not saying the court got it wrong; as you note, without seeing the transcript, I don't know exactly how the expert justified his conclusion. Rather, I'm saying that the court was applying the wrong (too liberal) standard, and the reasoning the court gave was adequte to meet that standard, but not Rule 702.
5.7.2006 2:15pm
Professor Bernstein,

But I just don't see how you can claim that the Riley Court applied the wrong standard. The court considered both the general reliability of the method as well as how the expert applied the method to the facts of the case. The court did not, as you seem to claim, accept a merely arbitrary application of the method, because the expert explained his reasons for eliminating the other causes.

So, it seems to me that you are left with nothing but a possible criticism of these decisions on the merits (eg, you seem to think both that "differential diagnosis" is generally unreliable, and also that the expert did not reliably apply the method to this case). But I see no indication that the Riley Court failed to apply the modern Rule 702 as written--the court just reached a different conclusion on these issues.
5.7.2006 2:25pm
davidbernstein (mail):
The court said that expert testimony is admissible unless it would be of absolutely no help to the trier of fact, and that flaws in differential etiology go to weight, not admissibility. That's not the right standard. Meanwhile, the fact that "the expert explained his reasons for eliminating the other causes" hardly makes for a reliable means of determining causation.
5.7.2006 4:20pm
Professor Bernstein,

It seems to me that you are continuing to mislead your readers by implying that the passages you are noting are the sum total of the court's reasoning. Again, the court did in fact quote modern Rule 702, and I have cited the passages where the court did everything modern Rule 702 requires. At this point, though, I'd suggest to interested readers that they look at the opinion for themselves, and make up their own minds about whether the court merely "payed lip service" to the rule, or rather whether the court did in fact apply the rule as written.

By the way, Step 3 of the Rule 702 analysis requires the court to determine if the methodology has been reliably applied to the facts of the case. Given the method in question, it should be obvious that how the expert went about eliminating other possible causes is precisely what the court must look at in order to the determine whether the expert reliabily applied this method to the facts of the case. And once the Riley Court determined that the expert reliably applied a generally reliable method to the facts of the case, that is where its Rule 702 inquiry properly ended.

Again, it seems to me that you really just don't like the method of "differential diagnosis", and are trying to relitigate that issue. But rather than simply state your objections to this methodology, you are trying to mislead your readers into thinking that this court somehow ignored the requirements of Rule 702, rather than simply reaching a different conclusion than you might have reached on the merits.

But again, I think your readers should be well-equipped to judge for themselves at this point what actually happened in this opinion.
5.7.2006 4:51pm