On July 17,
I observed that
At a webinar on probabilistic genotyping organized by the FBI, the Department of Justice’s Senior Advisor on Forensic Science, Ted Hunt, summarized the rules of evidence that are most pertinent to scientific and expert testimony. In the course of a masterful survey, he suggested that Federal Rule of Evidence 704 somehow conflicts with the evidence-centric approach to evaluating laboratory results recommended by a subcommittee of the National Commission on Forensic Science, by the American Statistical Association, and by European forensic-science service providers.
I proceeded to analyze Rule 704 and its application to the conclusion-centric testimony used in US courts. In a comment posted on July 21 (and reproduced below), Mr. Hunt generously took the time to respond. Taken together, his webinar presentation, my posting on it, and his comment on this blog discuss three issues:
(1) What does Rule 704 reveal about the proper or permissible role of an expert witness?
(2) Are certain publications on the desirability of the evidence-centric approach deficient or misleading for failing to mention Rule 704?
(3) Does Rule 704 pertain to every source-attribution opinion?
As explained below, the short answers are "not much," "no," and "no," respectively. In addition, an
essay on the first and third issues will appear in the Winter 2020 issue of
Jurimetrics Journal.
I
Mr. Hunt commented that “I don’t disagree that Rule 704 ‘does not counsel in favor’ of admitting expert opinion on an ultimate issue. I never said or implied anything or the sort.” At the same time, he wrote that “the Federal Rules (and most state rules of evidence) affirmatively allow an expert to offer an opinion about a proposition.”
Listening to the talk, I thought I was hearing the germ of a legal argument that Rule 704 not only allows, but also
affirmatively supports the admission of source-attribution opinions such as “I am sure that the defendant is the source of the latent print.” The recording of the webinar is on the Forensic Technology Center of Excellence
website, I transcribed the two small parts that pertain to Rule 704. I think I have captured all the words on Rule 704 and source opinions; they are in Appendix A.
The talk begins with a reference to “lots of statements” on the role of the expert witness “that have been pushed out in the literature” and therefore merit “a deeper dive and look at the American judicial system and the role of the expert in it.” After reviewing the most important rules affecting expert and scientific testimony generally, Mr. Hunt quoted several statements from organizations to the effect that experts ought to explain the degree to which the scientific data support the relevant hypotheses (“propositions” about the source of the data) rather than opine on the truth of the hypotheses themselves. Various forensic scientists, psychologists, law professors, and others have been advocating this approach for decades.
Mr. Hunt cautioned the audience as follows:
However, in the US system there is Rule 704, which is a rule that you don't hear much about, and I think there are some people who would like to pretend that it doesn't exist, but it actually goes against that school of thought and allows an expert to opine on an ultimate contested proposition before the court, not only on the strength of the evidence for or against the proposition. Specifically an opinion is not objectionable just because it embraces an ultimate issue, and you can add proposition in there as well.
He concluded his exposition of Rule 704 with the observation "So in the DNA context this would allow a source-attribution statement" and then described a few cases that accepted DNA source conclusions.
To my ear, the suggestion that people are pretending that Rule 704 does not exist because "it actually goes against that school of thought" sounded like an argument that Rule 704 is an affirmative reason for a court to allow traditional source-attribution testimony. My criticism of this argument (whether or not it was Mr. Hunt's) had two components. First, sometimes source opinions are not opinions on "ultimate" issues or facts—things like whether the killer was insane or whether the deceased committed suicide. In those cases, the rule does not even come into play.
Second, to say that Rule 704(a) "allows" source attributions is merely to say that a previous and ill-defined common-law rule on opinion testimony is no longer a reason to exclude the testimony. Rule 704(a) just cancels out a categorical rule of exclusion, leaving the court with a big zero. The rule does not militate either for or against the idea that forensic scientists should avoid proffering source opinions. It merely means that the objecting party had better have some other reason for the court to exclude the opinion.
This much is true whether the issue or fact is called ultimate or intermediate. Parties opposing source-attribution opinions could argue for exclusion under the helpfulness requirement of Rule 702 or the balancing mandated by Rule 403. The documents cited by Mr. Hunt do not invoke these rules, just as they do not discuss Rule 704, because they are not making a legal argument.
In emphasizing that Rule 704 is merely a rule of non-exclusion, I hasten to add that I am not suggesting that Mr. Hunt misrepresented the rule as mandating admission of ultimate-opinion testimony. He did nothing of the kind. The undisputed legal principle is that Rule 704 is agnostic toward ultimate-opinions. As Mr. Hunt agreed, it does not counsel in favor of their admission. Once that much is understood, readers can decide for themselves whether the rule “actually goes against that school of thought” that asks criminalists to avoid expressing opinions on the truth of hypotheses.
II
To emphasize that he was not suggesting "that Federal Rule of Evidence 704 somehow conflicts with the evidence-centric approach to evaluating laboratory results," as I originally put it, Mr. Hunt explained that he only was trying to correct a possible misunderstanding of what he called the "role assignment" documents:
My comments about FRE 704 were directed to the claim of ‘role assignment’ by the authors of the cited sources. The documents I cited (ENFSI, Evett, NIFS, AFSP, NCFS, ASA) make statements such as ‘the role of the expert is to comment on the probability of their findings, given these propositions and not on the propositions themselves.’ (NIFS).
I simply noted that this purported assignment of ‘roles’ is more limited than that which is permitted by the Federal Rules of Evidence. None of these documents concede (or even acknowledge) that the Federal Rules (and most state rules of evidence) affirmatively allow an expert to offer an opinion about a proposition, rather than limiting that opinion to the relative strength of the evidence in support of competing propositions.
Omitting this information may mislead some to believe that the ‘role’ assigned by these documents to an expert is instead assigned by legal rules, rather than a ‘best practices’ world view.
***
In conclusion, to the extent there is any ‘tension’ or ‘inconsistency’ between Rule 704 and the noted references, it was created by the referenced documents’ omission of a discipline-specific basis for their claim that ‘the role of the expert is to comment on the probability of their findings, given these propositions and not on the propositions themselves.’ Each of the cited sources fail to make it clear that this limited ‘role’ is self-imposed, not legal in nature. That was the point of my observation.
Informing people that the law allows well founded source-attribution opinions is entirely reasonable. Only a few courts depart from that generalization. But the position papers and guides to evaluative reporting with which I am familiar surely are not deficient, deceptive, or misleading about this.
The document from which the quoted words, "role of the expert," come is the
Introductory Guide to Evaluative Reporting prepared by a special committee created by the
National Institute of Forensic Science. NIFS is a directorate within the Australian and New Zealand Policing Advisory Agency (ANZPAA). The "role assignment" language occurs within a box contrasting "traditional reporting" and "evaluation using a logical framework." I don't care for the phrase "logical framework" (to the extent it intimates that nothing else is logical), but the words "role of the expert" are appropriately used only to refer to
the role of the expert within the stated alternative to the traditional approach. Let’s put the words back into the full sentence in which they occur (with the language that Mr. Hunt questioned in bold):
The fundamental principles of evaluative reporting or interpretation are that (i) the crime must be considered to have occurred within a framework of circumstances, (ii) that the findings must be considered in light of at least two competing propositions that will be guided by the case circumstances and (iii) that the role of the expert is to comment on the probability of their findings, given these propositions and not on the propositions themselves. (P. 6).
The first page of the NIFS
Guide explains that the purpose is to introduce readers to
an alternative to traditional and continuing practice and to “provide[] managers with advice on implementing evaluative reporting
where they consider it appropriate.” (P. 1, emphasis added). A "discipline-specific basis for their claim" that reporting likelihoods has cross-disciplinary advantages over elimination-versus-identification opinions would make little sense in a document designed to enable "many traditional comparative forensic disciplines" to produce reports and testimony in "ways that can be standardised between analysts within, and between, organisations and forensic disciplines." (P. 6).
Little would be gained by reviewing the details of the other documents Mr. Hunt feels should have "conceded" or "acknowledged" the existence of Rule 704. I cannot see how many readers of these documents could construe them as describing the current rules of U.S. evidence law (or that of other countries),
1/ but it is always good to to distinguish between legal and statistical or scientific principles.
Adhering to this distinction, there is a legal argument for the role that the documents recommend for the expert. Proponents of this “likelihood-ratio” or “Bayes-factor” mode of presentation believe that it nicely captures the role of a scientist supplying the legal factfinder with information based strictly on the physical or chemical features of the specimens that are compared. DNA experts do not normally testify that the defendant's DNA is present in the crime-scene DNA. Instead, they testify to probability of the measured quantities of identifying DNA fragments (or to the probability of the alleles inferred from these measurements)
if the defendant's DNA is not present in the sample. They also may testify to the probability
if it is, or to the ratio of these probabilities.
To reach the further conclusion that the defendant's DNA actually is in the questioned sample would require information outside of the fragment lengths measured in the laboratory. In Bayesian terms, any conclusion about the true source "necessarily rests, in part, on an implicit assessment or assumption about the prior odds that the suspect is the source," and “[m]aking those assessments or assumptions takes forensic scientists beyond their scientific expertise in ways that arguably usurp the role of legal fact-finders."
2/ The core of the argument is that experts exceed their legally assigned role of assessing the physical evidence when they venture beyond the scientific data to which the likelihood ratio pertains. "Experts are rarely in a good position to evaluate the prior odds that the items they are comparing have a common source, and arguably have no business doing so."
3/
That criminalists dealing with other types of evidence were implicitly opining on prior probabilities beyond their expertise was not obvious in the days when it was thought that every specimen—I'll use fingerprints as an example—is unique. Uniqueness of prints makes it sound as if the criminalist does not have to think about the population from which a latent print came in order to conclude that the print had to be the defendant's. But uniqueness of friction ridge skin is not a sufficient basis for a source attribution. It overlooks the fact that latent print examiners do not deal with three-dimensional skin. They compare impressions of a complete and clear set of prints to incomplete and often low quality impressions. The two-dimensional representations vary from one impression to the next. The only question the analyst can answer strictly on the basis of the features (and knowledge of their joint distribution in a relevant population) is how the probability of a latent print being as similar as it is to the exemplar print—when it is, in fact, from the finger that produced the exemplar print—compares to the probability of the latent print being so similar when it is from someone else's finger.
This "role-assignment" argument is not conclusive. What if
experts legitimately can say that in every relevant population of plausible
size, the probability is very high that only one finger could have
produced the observed features? Or that the likelihood ratio is so huge
that it swamps the prior probability for an individual randomly drawn
from that population? Then the expert who
indulges in source attribution (without specifying a prior probability for the judge or jury to consider) arguably would not exceed the role of the expert defined in
Federal Rule of Evidence 702.
III
Moving back to the content of Rule 704, it seems that we have a sharp disagreement about the reach of the "ultimate issue" rule that Rule 704 (building on earlier case law and academic criticism) decisively rejected. The rule applies to any opinion from any witness—expert or lay—that "embraces an ultimate issue." But what does that phrase mean? I maintained that Rule 704 does not apply to
all source attributions because "the identity of the source of a trace is not
necessarily an ultimate issue." To make this point, I wrote as follows:
To use the example of latent-print identification given in the webinar, the traditional opinion that a named individual is the source of a print is not an opinion on an ultimate issue. Courts have long allowed examiners to testify that the print lifted from a gun comes from a specific finger. But this conclusion is not an opinion on whether the murder defendant is the one who pulled the trigger. The examiner’s source attribution bears on the ultimate issue of causing the death of a human being, but the examiner who reports that the prints were defendant's is not opining that the defendant not only touched the gun (or had prints planted on it) but also pulled the trigger. Indeed, the latent print examiner would have no scientific basis for such an opinion on an element of the crime of murder.
Mr. Hunt's comment insists that every source attribution is an ultimate-issue opinion to which Rule 704 applies. Here is his argument:
[Y]our blog states that ‘the identity of the source of a trace is not necessarily an ultimate issue.’ As evidence for that assertion, you used my latent print example, claiming that ‘the traditional opinion that a named individual is the source of a print is not an opinion on an ultimate issue.’
Your claim is directly contrary to the contents of the judicial opinion I cited in the questioned slide, which states in full: ‘[Defendant] . . . contends that the district court erred in allowing the expert to specifically testify that he had no doubt that the prints on the parking stub were [Defendant’s] because the expert was testifying to the "ultimate issue’ of whether it was Sherwood's print. This argument fails in light of Fed. R. Evid. 704, which permits expert testimony on the ultimate issue in a case.” United States v. Sherwood, 98 F.3d 402, 408 (9th Cir. 1996).
In Sherwood, the ultimate issue was not described as a connection between the latent print and activity-level behavior; rather, it was the expert’s testimony about the source of that print. Your description of an ultimate issue as limited to one in which (using your example), ‘the murder defendant is the one who pulled the trigger’ is a narrower description of the types of factual assertions entailed by Rule 704 than those described throughout case law. As such, your explanation of the Rule is not entirely correct.
For other examples of courts describing identification testimony as ‘ultimate’ in nature, see U.S. v. Rose, 731 F.2d 1337, 1346-47 (print match to shoe) United States v. Bice-Bey, 701 F.2d 1086 (4th Cir. 1883) (voice identification); United States v. Sellers, 566 F.2d 884 (4th Cir. 1977) (identification of suspect in a picture); United States v. Couser, 15 Fed. R. Evid. Serv. (CBC) 837 (4th Cir. Apr. 5, 1984) (comparison of suspect’s features to photograph). These cases clearly demonstrate that source identification testimony constitutes an opinion that embraces an ‘ultimate’ fact.
It is true that the Ninth Circuit in
Sherwood referred to the source attribution as an "ultimate" opinion. I assume every other case he lists did the same. However, this use of authority is an instance of looking for law in all the wrong places. Every time a party objects, "Your honor, my identity as the source of the trace is an ultimate issue!", the court can summarily reject the objection by citing Rule 704's text. Why bother to try to trace the boundaries of the "the so-called 'ultimate issue' rule" (Fed. R. Evid. 704 Advisory Committee's Note) when the murky rule "is specifically abolished" (
id.)? Regardless of the reach of Rule 704, the outcome is the same. If the expert opinion is outside the old rule, then it is "not objectionable" just because it embraces an ultimate issue. If it is covered by the old rule, it is "not objectionable" because the old rule is no longer a barrier.
So the fact that modern courts often assume—without analysis—that a source opinion is ultimate-opinion testimony tells us next to nothing about how the opinion would have fared under the defunct common-law exclusionary rule. To answer that arcane question, we must look to the old cases applying that rule to exclude opinion testimony.
Where should we begin?
McCormick on Evidence § 12, at 80 (7th ed. 2013), documents the "general doctrine that witnesses may never give their opinions or conclusions on an ultimate fact in issue" with two cases:
United States v. Spaulding, 293 U.S. 498 (1935), and
State v. Carr, 196 N.C. 129, 144 S.E. 698 (1928). In
Spaulding the "ultimate issue" was whether the plaintiff was totally disabled while an insurance policy was in force. He produced "medical opinions" that he "became totally and permanently disabled before his policy lapsed." The Supreme Court wrote "that question is not to be resolved by opinion evidence. It was the ultimate issue ... . The experts ought not to have been asked or allowed to state their conclusions on the whole case." 293 U.S. at 506.
Carr is a homicide case. The defense was that a man who died in bed of a gunshot wound had committed suicide. The state produced a medical doctor who testified that "I don't think it is possible for the deceased to have fired the gun and made the wound that I saw." 144 S.E. at 700. The North Carolina Supreme Court held that the trial court erred in admitting the opinion. It explained that
[T]he opinion or inference of the witness must not be an answer to the exact issue which the jury is to determine. When the witness testified that he did not think it possible for the deceased to have fired the gun and to have made the wound he necessarily testified in effect that in his opinion the deceased did not kill himself. True, the "exact issue" was whether the defendants are guilty, but if the deceased killed himself the conclusion that the defendants did not kill him would necessarily follow.
Id. These cases reveal that the essence of the ultimate-issue rule is that the witness may not opine on a fact that determines whether an element of the offense or complaint, or of the defense, is satisfied.
Other facts are intermediate. They are links in a chain of reasoning that terminates in the answer to one of these ultimate issues. In an action for a declaration of paternity, for example, an expert opinion that (based on DNA tests) the defendant is the father, falls under the former ultimate-issue rule. But suppose the government introduces an expert opinion that a murder defendant is the father of a fetus whose remains were found along with the mother's merely to show that he had a motive to kill the mother, who refused to have an abortion as he had demanded. Now the source conclusion is not an opinion on an ultimate issue. The jury can accept the source opinion but conclude that defendant, despite the motive, was not the killer. In contrast to
Spaulding, the expert opinion does not decide "the whole case." Unlike
Carr, the ultimate conclusion does not "necessarily follow."
On which side of the ultimate-intermediate line the examiner's opinion in
Sherwood falls I cannot say. The opinion is too sparse. But the question is academic. One purpose of Rule 704 is to spare the courts from having to pin these labels on opinion testimony. (See Advisory Committee's Note, observing that the old rule was "difficult of application"). With the rule in place, they can just say "so what—the argument fails in light of Rule 704." But that does not mean that a source opinion is always an opinion on "an ultimate issue." That depends on how the opinion fits into the case.When the source opinion is near enough to the "ultimate" endpoint, Rule 704 does not say, "OK, let it in." In conjunction with Rule 702, it says "Well, yes, but there is no mechanical rule excluding it on that basis alone—just address how helpful it is for the jury to hear it."
When courts address the question of helpfulness, they just might conclude that instead of old-style source attributions, statements about the probabilities of the findings under different hypotheses would fulfill the role of
helping the factfinder find the facts better that traditional expressions of an examiner's belief that the defendant is the source of the trace. Or they might not. Either way, no one is trying to deny that Rule 704 exists. Why would they when it sheds so little light on the choice between traditional conclusion-centric opinons (source attributions that, to a Bayesian, reflect an expert's personal prior probabilities and utilities) and evidence-centric ones (such as Bayes factors that enable experts to express the probative value of the findings without venturing into that nonscientific territory)?
NOTES
-
Australia's uniform Evidence Acts § 80(a), adopted by many of its jurisdictions, abolished the common-law rule against ultimate opinions ("[e]vidence of an opinion is not inadmissible only because it is about—a fact in issue or an ultimate issue."). New Zealand did the same in its 2006 Evidence Act ("(2) An opinion by an expert is not inadmissible simply because it is about—(a) an ultimate issue to be determined in a proceeding; or (b) a matter of common knowledge.").
- William C. Thompson, How Should Forensic Scientists Present Source Conclusions?, 48 Seton Hall L. Rev. 773, 791 (2018).
-
Id.; see also David H. Kaye et al., The New Wigmore, A Treatise on Evidence: Expert Evidence § 2.2.2, at 44 (2d ed. 2011) (notes omitted):
But this form of opinion leaves the jury with an inappropriate choice. If the jury is to accept the opinion on a matter within the witness’s expertise, it must also accept the expert’s (presumably unarticulated) assessment of evidence that has nothing to do with the expertise and that falls within the jury’s ability to asses. Or, it must accept an unvalidated and implausible theory of individualization.
APPENDIX A
Ted R. Hunt, The Expert’s Role in the American Judicial System (Probabilistic Genotyping of Evidentiary DNA Typing Results – An Online Workshop Series, Module 8: Probabilistic Genotyping Summation and Special Topics, July 17th, 2019, available at https://forensiccoe.org/ (excerpt of all remarks on Rule 704 and source conclusion testimony)
*** My talk is entitled "the role of the expert" because there aren't special rules that just apply to DNA analysts and no one else, and the reason that I want to talk about it today is, in the forensic literature in the last number of years, lots of statements have been made about the role of the courts and the role of the experts, and those statements aren't specific to any judicial system. They're pretty much general statements that have been pushed out in the literature so I thought we'd take a deeper dive and look at the American judicial system and the role of the expert in it.
***
Now I mentioned before at the beginning of this talk there's a lot of literature on the role of the courts and the role of the expert in the forensic literature. I have some examples here. The European Network has its guidelines for evaluative reporting in forensic science. Number 3 here in this excerpt talks about the role of the forensic practitioner to consider the probability of the findings considering the propositions and not the probability of those propositions. Similarly, other documents in the community from Australia and New Zealand, from Dr. Evett, from the Association of Forensic Science Service Providers. All basically say the same thing, talking about the role of the expert to comment on the probability of the findings given those propositions and not the prepositions themselves.
This has gotten into the US forensic community to a certain extent. On the left is the National Commission [on Forensic Science] Views Document. I just want to be clear this document did not get voted to approval through the Commission, but nevertheless there is a final stand-alone version to that document that basically says the same thing: Forensic practitioners should not state that a specific individual or object is the source of forensic evidence and refers to the formal method of evaluative reporting as well. And basically the same people who wrote that document wrote the American Statistical Association document which, for the most part, says the same thing, discouraging the statements to the effect that a specific person or object is the source of evidence.
However, in the US system there is Rule 704, which is a rule that you don't hear much about, and I think there are some people who would like to pretend that it doesn't exist, but it actually goes against that school of thought and allows an expert to opine on an ultimate contested proposition before the court, not only on the strength of the evidence for or against the proposition. Specifically an opinion is not objectionable just because it embraces an ultimate issue, and you can add proposition in there as well.
I need to add that 704 does not lower the bar to admit otherwise inadmissible evidence. It will work in conjunction with the other rules of evidence. The only exception in the American system or the US federal system is that the expert may not opine on the defendant's mental state —an ultimate legal proposition before the court—or witness credibility. However, they can opine on an ultimate issue.
Just as an example, this is a latent fingerprint case from the 9th circuit in 1996 [United States v. Sherwood, 98 F.3d 402 (9th Cir. 1996)] and a defendant objected that an expert was specifically testifying that he had no doubt that the prints on the piece of evidence were the defendant’s. The defendant objected because the expert was testifying to an ultimate issue, and the court basically said, so what—the argument fails in light of 704, which permits an expert to opine on ultimate issues.
Like I said before, I’m trying to be very descriptive. I’m not being normative, and I’m not weighing in on the logic or the advisability of this. I'm simply trying to correctly state what I understand the law to be.
So in the DNA context this would allow a source attribution statement. ***
APPENDIX B
Comment posted to this blog, July 21, 2019
Professor Kaye,
My comments about FRE 704 were directed to the claim of ‘role assignment’ by the authors of the cited sources. The documents I cited (ENFSI, Evett, NIFS, AFSP, NCFS, ASA) make statements such as ‘the role of the expert is to comment on the probability of their findings, given these propositions and not on the propositions themselves.’ (NIFS).
I simply noted that this purported assignment of ‘roles’ is more limited than that which is permitted by the Federal Rules of Evidence. None of these documents concede (or even acknowledge) that the Federal Rules (and most state rules of evidence) affirmatively allow an expert to offer an opinion about a proposition, rather than limiting that opinion to the relative strength of the evidence in support of competing propositions.
Omitting this information may mislead some to believe that the ‘role’ assigned by these documents to an expert is instead assigned by legal rules, rather than a ‘best practices’ world view. I never said or implied that Rule 704 ‘stands in the way’ of an expert’s provision of a more limited opinion about the strength of the evidence relative to competing propositions.
In addition, your blog states that ‘the identity of the source of a trace is not necessarily an ultimate issue.’ As evidence for that assertion, you used my latent print example, claiming that ‘the traditional opinion that a named individual is the source of a print is not an opinion on an ultimate issue.’
Your claim is directly contrary to the contents of the judicial opinion I cited in the questioned slide, which states in full: ‘[Defendant] . . . contends that the district court erred in allowing the expert to specifically testify that he had no doubt that the prints on the parking stub were [Defendant’s] because the expert was testifying to the "ultimate issue’ of whether it was Sherwood's print. This argument fails in light of Fed. R. Evid. 704, which permits expert testimony on the ultimate issue in a case.” United States v. Sherwood, 98 F.3d 402, 408 (9th Cir. 1996).
In Sherwood, the ultimate issue was not described as a connection between the latent print and activity-level behavior; rather, it was the expert’s testimony about the source of that print. Your description of an ultimate issue as limited to one in which (using your example), ‘the murder defendant is the one who pulled the trigger’ is a narrower description of the types of factual assertions entailed by Rule 704 than those described throughout case law. As such, your explanation of the Rule is not entirely correct.
For other examples of courts describing identification testimony as ‘ultimate’ in nature, see U.S. v. Rose, 731 F.2d 1337, 1346-47 (print match to shoe) United States v. Bice-Bey, 701 F.2d 1086 (4th Cir. 1883) (voice identification); United States v. Sellers, 566 F.2d 884 (4th Cir. 1977) (identification of suspect in a picture); United States v. Couser, 15 Fed. R. Evid. Serv. (CBC) 837 (4th Cir. Apr. 5, 1984) (comparison of suspect’s features to photograph). These cases clearly demonstrate that source identification testimony constitutes an opinion that embraces an ‘ultimate’ fact.
I don’t disagree that Rule 704 ‘does not counsel in favor’ of admitting expert opinion on an ultimate issue. I never said or implied anything or the sort.
In conclusion, to the extent there is any ‘tension’ or ‘inconsistency’ between Rule 704 and the noted references, it was created by the referenced documents’ omission of a discipline-specific basis for their claim that ‘the role of the expert is to comment on the probability of their findings, given these propositions and not on the propositions themselves.’ Each of the cited sources fail to make it clear that this limited ‘role’ is self-imposed, not legal in nature. That was the point of my observation.
Thanks for your participation in the webinar series and for your interest in my talk.
Ted R. Hunt
Senior Advisor on Forensic Science
U.S. Department of Justice
