July 03, 2024—Most criminal defense attorneys have encountered efforts by prosecutors to elicit “expert opinions” from law enforcement agents at trial that, in essence, the Defendant’s actions conform to that of a person intending to commit the crime charged.
Until recently, it appeared axiomatic that the admission of such testimony would violate Federal Rule of Evidence 704(b), which provides that, “[I]n a criminal case, an expert witness must not state an opinion about whether the defendant did or did not have a mental state or condition that constitutes an element of the crime charged or of a defense.”
However, the Supreme Court has all but gutted the protection offered by F.R.E. 704(b) in Diaz v. United States, No. 23-14 (June 20, 2024). This piece maintains that though Diaz has weakened F.R.E. 704, practitioners can still preclude the admission of such troubling expert opinion testimony pursuant to Federal Rule of Evidence 702.
The holding in Diaz
Delilah Diaz was a California resident who was stopped by Border Patrol crossing the border from Mexico into the United States. Agents found 24.82 kilograms of pure methamphetamine and two cell phones in the car Diaz was driving. Diaz told Border Patrol (https://bit.ly/4eKrzIn) that the car was her boyfriend’s and that she was unaware of the drugs. Nonetheless, Diaz was indicted for drug trafficking pursuant to 21 U.S.C. § 952 (https://bit.ly/3W48IAM) and § 960 (https://bit.ly/3W1EjTB).
At trial, the District Court permitted Homeland Security Investigations Special Agent Andrew Flood to testify as an expert witness and to opine that drug traffickers “generally do not entrust large quantities of drugs to people who are unaware they are transporting them.”
Noting that Rule 704(b) applies “only to opinions about the defendant,” the Supreme Court affirmed, reasoning that, “[B]ecause Agent Flood did not express an opinion about whether Diaz herself knowingly transported methamphetamine, his testimony did not violate Rule 704(b)”. Id.
In light of Diaz, practitioners need to rely on F.R.E. 702
Diaz will undoubtedly render F.R.E. 704 essentially impotent. However, Diaz did not address the admissibility of the testimony at issue under F.R.E. 702. As such, practitioners continue to possess an important shield against the admission of such concerning “opinion” testimony.
Federal Rule of Evidence 702 sets forth the requirements for the admission of expert opinion testimony. As a preliminary matter the Rule requires that the witness be “qualified as an expert by knowledge, skill, experience, training, or education.” Id.
If so, then the witness may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that: (a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data;(c) the testimony is the product of reliable principles and methods; and (d) the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case. Id.
As the Supreme Court made abundantly clear in Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 914 (1993), F.R.E. 702 requires district courts to perform a critical “gatekeeping” function concerning the admissibility of scientific, technical, or experientially-based expert evidence. See also Kumho Tire v.
Carmichael, 526 U.S. 137 (1999).
Indeed, “[T]he objective of that requirement is to ensure the reliability and relevancy of expert testimony. It is to make certain that an expert, whether basing testimony upon education or personal experience, employs in the courtroom the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.” Id. at 152.
Thus, the power of expert testimony makes the district court’s role especially significant since such opinion testimony “can be both powerful and quite misleading because of the difficulty in evaluating it.” Id. at 595 (quoting Jack B. Weinstein, Rule 702 of the Federal Rules of Evidence is Sound; It Should Not Be Amended, 138 F.R.D. 631, 632 (1991)).
An expert may only testify with respect to sufficiently reliable matters upon which the expert is qualified to testify.
The guidance contained in Daubert provides an invaluable tool to challenge: 1) the qualifications of any proposed “expert”; 2) the qualification to render the opinion at issue, 3) the basis of the opinion, and 4) the helpfulness of the opinion to the jury. Indeed, as explained in Daubert, “[T]he proponent of the expert testimony carries a substantial burden under Rule 702.”
In summary, the proponent of the expert opinion must establish that the witness is “qualified to testify competently, that his opinions are based on sound methodology, and that his testimony will be helpful to the trier of fact.” Id., at 1107.
On point, it is inconceivable that Agent Flood’s experience in the field could be sufficient to opine that “most” couriers are aware that they are transporting drugs, unless he has been a one-man DEA agency for the last several decades. One would also assume that there is no statistical data supporting the opinion. Thus, Agent Flood’s credentials and the basis for his opinion remain subject to challenge pursuant to F.R.E. 702 even if F.R.E. 704(b) fails to provide the desired protection.
Further, expert opinion testimony is inadmissible under F.R.E. 702 when it offers nothing more than what lawyers for the parties can argue in closing arguments. See 4 Weinstein’s Federal Evidence § 702.03[2] [a]. Generally, expert testimony is only admissible under Rule 702, “if it concerns matters that are beyond the understanding of the average lay person.” See United States v. Rouco, 765 F.2d 983, 995 (11th Cir.1985) (expert testimony admissible if it offers something “beyond the understanding and
experience of the average citizen”).
The opinion testimony at issue in Diaz appears to have been based on common sense rather than statistical information or specialized experience. Indeed, the Court noted that Agent Flood testified that, “to use an unknowing courier would expose the drug-trafficking organization to substantial risk.” Id. at 3 4.
The Court also noted that, “Even if the drugs reached the intended destination, the organization would then have to retrieve the drugs without detection.” Id. The fact that the opinion is based on mere logic, and not hard data, makes its admission as “expert opinion testimony” dubious.
In fact, in his dissent in Diaz, Justice Neil Gorsuch powerfully made this point, stating, “Nor does testimony like that help the jury understand “’experience[s] confessedly foreign in kind to [its] own.’” He added, “Jurors are more than up to performing that task, and they hardly need the help of some clairvoyant.” Diaz, dissent at 13–14.
Conclusion
The Court’s analysis in Diaz was limited to F.R.E. 704(b), and while disappointing, the case is not dispositive as to the admissibility of similar testimony under an expanded analysis pursuant to F.R.E. 702.
When properly challenged in a pre-trial Daubert motion, prejudicial expert opinion testimony can still be properly precluded from admission. Accordingly, practitioners should continue to challenge the admissibility of similarly concerning expert opinion evidence, pointing out the limited scope of the Diaz Court’s analysis and asking the trial Court to exercise its gate-keeping function as ascribed to it in Daubert.
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