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United States v. Mouzone, 687 F.3d 207 (4th Cir. 2012)

Case (cite)
United States v. Mouzone, 687 F.3d 207 (4th Cir. 2012)
Type of proceeding
Type of claim
Type of claim (second claim)
Expert evidence ruling reversing or affirming on appeal:
What was the ruling?
No Error due to Harmless Error
Type of evidence at issue:
Firearms identification
Defense or Prosecution Expert
Name of expert(s) who were the subject of the ruling
Mark Ensor
Summary of reasons for ruling
Defendants argue that the expert's testimony violated the district court's order on limiting testimony by emphasizing the certainty of the testimony and that this was unfairly prejudicial by portraying the defendants as killers. The court disagreed and held that the expert testimony was "incapable of effectuating the prejudice" because it only supports the notion that the bullets recovered from each murder scene were fired from the same weapon, not that either defendent was responsible for the murder or that because they were guilty of one murder they were guilty of another. Therefore, if the jury concluded that defendants were the murderers, the expert testimony was not the cause of that conclusion. Because the court finds any error would be harmless, they decline to decide whether the court erred.
The jurisdiction’s standard for expert admissibility at the time – list all that apply: (Frye), (Daubert), (Post-2000 Rule 702), (Other)
Second standard
Did lower court hold a hearing
Names of prosecution expert(s) two testified at hearing
Names of defense expert(s) who testified at hearing (or None).
Discussion of 2009 NAS Report (NAS2009)
Discussion of 2016 PCAST report (PCAST)
Discussion of error rates / reliability
Frye Ruling
Limiting testimony ruling
Language imposed by court to limit testimony
Ruling based in prior precedent / judicial notice
Daubert ruling emphasizing – which factors – (list 1-5)
Ruling on qualifications of expert
Ruling on 702(a) – the expert will help / assist the jury
Ruling on 702(b) – the testimony is based on sufficient facts or data
Ruling on 702(c) – the testimony is the product of reliable principles and methods
Ruling on 702(d) – reliable application of principles and methods to the facts of the case


Note: it does appear the district court allowed the expert to testify in vioaltion of the order limiting his testimony. See below:

When Ensor testified, he stated repeatedly that the casings were “fired from the same firearm.” At one point he said, “If I go around this breech face and see that all these markings are matching up and phase with each other, the chances of that happening in a random fashion on two different surfaces, there comes a point where it’s a practical impossibility…. That’s when I’m convinced that these two [cartridge cases] were marked by the same surface.” Defense counsel entered multiple objections during Ensor’s testimony, but the district court overruled all of them.