Challenging Gunshot Residue Expert Testimony

Expert testimony concerning the presence of gunshot-residue evidence is admissible when the trial judge deems the opinion reliable, leaving for the jury, what if any, weight to give to the testimony; other challenges to the expert testimony are considered and rejected, in United States v. Stafford, _ F.3d _ (6th Cir. June 11, 2013) (No. 12-3238)

Many forms of expert testimony cannot definitively resolve certain issues but may lead to an inference toward a certain conclusion. For example, a handwriting expert may be permitted to opine that certain handwriting is "probably" (but not "definitely") authored by a particular individual after comparing a handwriting exemplar to a known document. See generally Third Circuit: Expert Testimony Need Not Reflect A “Reasonable Degree Of Scientific Certainty"; Handwriting Expert Testimony Satisfied Five Daubert Reliability Factors. The Sixth Circuit recently considered a challenge to gunshot-residue expert testimony based on a lack of certainty about the conclusions.

Trial Court Admission Of Expert Testimony

Defendant Akeem Stafford was prosecuted for being a felon in possession of a firearm and ammunition. He became a suspect after an officer heard a gunshot near nightclub. The officer saw a man fire two more rounds. The man ran, was pursued and ultimately arrested without a firearm. Officers later recovered a .45 caliber semi-automatic firearm and .45 caliber shell casings near the location of the shooting. One bullet had struck a car passenger window. During booking, the man, who was identified as Stafford, has his hands swabbed to check for any gunshot residue. Further testing confirmed the presence of six gunshot-residue particles on the defendant’s left hand. Before trial, the defendant’s motion to exclude expert testimony and analysis about the gunshot-residue was denied. The jury convicted the defendant. He filed a post-trial motion for a new trial contesting the admission of the gunshot-residue evidence and expert testimony, which was denied. See Memorandum of Opinion and Order (No. 11-CR-44) (Oct. 19, 2011). The trial court noted that the gunshot-residue evidence was probative under FRE 401 to show that the defendant "fired the gun" and the results were not unfairly prejudicial under FRE 403 since the defendant "had an opportunity to present" concerns with the conclusions and evidence at trial. Under the Armed Career Criminal Act, the defendant received a sentence of 262 months of imprisonment. On appeal he renewed his challenge to the expert testimony.

Circuit Review Of Four Grounds To Exclude The Expert Testimony

The Sixth Circuit affirmed the admission of the evidence and conviction, rejecting four arguments raised by the defendant. First, he claimed the expert testimony was incapable of “determin[ing] whether an individual fired a gun, was present when a gun was fired by someone else, or was merely in an environment in which [gunshot residue] existed” and therefore should have been excluded under FRE 702. Stafford, _ F.3d at _. The circuit clarified that the trial court’s role was not to “determine whether [the expert opinion] is correct, but rather [to determine] whether it rests upon a reliable foundation.” Stafford, _ F.3d at _ (quoting In re Scrap Metal Antitrust Litigation, 527 F.3d 517, 529-30 (6th Cir. 2008)). As the circuit explained this point:

The district court was clear when it admitted the expert testimony relating to the gunshot residue test: “Whether the jury will put any weight on either [expert], I don’t know, but [the Defendant’s] arguments go to the weight [of the evidence], not the admissibility.” The district court stated that allowing the expert to testify would allow vigorous cross-examination of the expert’s “vague conclusions” and the jury would then decide. In revisiting the issue on the second day of trial, the district court stated:

I am allowing the government to put [the expert’s testimony] in. But given that your own expert is going to say it is possible that he has got those two traces either because he was right near a shooter, [was] a shooter of a gun[,] or that he came into contact with residue, I am permitting the defense to point that out. The two go together.

Stafford, _ F.3d at _ (citations omitted).

As a second argument, the defendant contended the expert testimony should have been excluded since “[t]here is no consensus in the discipline as to how many particles . . . must be identified in order to report an item of evidence as positive for [gunshot residue].” Stafford, _ F.3d at _. The circuit noted that the defendant did not contest the presence of gunshot residue found on his hand. Further, he had cited to the Summary of the FBI Laboratory’s Gunshot Residue Symposium (May 31–June 3, 2005) which states that “[m]ost experts felt that even one particle is enough for a ‘positive’ result.” The expert trial testimony identifying “five qualifying particles” supported the reliability of the conclusion. Stafford, _ F.3d at _ (citing Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579, 594 (1993) (“Widespread acceptance can be an important factor in ruling particular evidence admissible.”)).

Finally, the defendant claimed the expert testimony should not have been admitted based on questions concerning the collection of the residue, in particular the policed department “fail[ed] to use proper evidence gathering techniques in testing for [gunshot residue].” There were a number of steps concerning the integrity of the evidence:

[The officers who] did not bag [the defendant’s] his hands; could have transferred gunshot residue to Stafford’s hands from handling their own weapons, from the backseat of the police car, or from the booking area of the Elyria Police Department; and did not swab Stafford’s hands until after he had been booked.

Stafford, _ F.3d at _. The circuit readily rejected this challenge as well:

These arguments, while potentially valid as to the accuracy of the test and the conclusions to be drawn from it, do not relate to the test’s reliability or the reliability of the expert testimony. Furthermore, Stafford’s arguments go to the weight of the gunshot-residue evidence, not its admissibility, which was properly considered by the jury. Again, the cross-examination of the expert at trial allowed the jury to consider the weight of the gunshot-residue evidence and any shortcomings in evidence collection by the Elyria Police Department. Therefore, the district court did not abuse its discretion in admitting the evidence.

Stafford, _ F.3d at _.


The Stafford case highlights common challenges to forensic expert testimony. As long as the expert testimony is reliable, normally the courts allow the jury to consider the evidence along with any cross-examination or challenges about the conclusions of the expert. The approach is consistent with the framework established by the Supreme Court in Daubert, 509 U.S. at 596 ("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.") (also cited by the trial court in Memorandum of Opinion and Order, at 5 (No. 11-CR-44) (Oct. 19, 2011)).


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