admit or exclude expert testimony, and their judgments are subject only to a highly deferential “abuse of discretion” standard of review.48

To get a clearer picture of judicial dispositions of Daubert-type questions, we need to know how these matters are handled by trial courts. Unfortunately, the picture is unclear. There are countless Daubert-type, evidentiary challenges in criminal cases, some resulting in formal Daubert hearings, and many others not. There is no way to know with any degree of certainty how many of these challenges are entirely or partially sustained, because many trial court judgments on evidentiary matters are issued without published opinions49 and with no appeal. If a defendant’s challenge is sustained and is followed by an acquittal, no appeal ensues and the matter is over. If a defendant’s challenge is sustained and is followed by a conviction, the defendant obviously will not appeal the favorable evidentiary ruling. If a defendant’s challenge is rejected and is followed by an acquittal, no appeal ensues and the matter is over. Reported opinions in criminal cases indicate that trial judges sometimes exclude or restrict expert testimony offered by prosecutors;50 reported opinions also indicate that appellate courts routinely deny appeals contesting trial court decisions admitting forensic evidence against criminal defendants.51 But the reported opinions do not offer in any way a complete sample of federal trial court dispositions of Daubert-type questions in criminal cases.52


Gen. Elec. Co. v. Joiner, 522 U.S. 136, 142-43 (1997); see also H.T. Edwards and L.A. Elliott. 2007. Federal Standards of Review. St. Paul, MN: Thomson/West, pp. 72-74 (explaining that when a trial judge acts pursuant to broad discretion, appellate court scrutiny is necessarily very limited).


See, e.g., Hoult, 57 F.3d at 5 (district courts are not required “to make explicit on-the-record rulings regarding the admissibility of expert testimony”); United States v. Locascio, 6 F.3d 924, 938-939 (2d Cir. 1993) (“We decline … to shackle the district court with a mandatory and explicit trustworthiness analysis…. In fact, we assume that the district court consistently and continually performed a trustworthiness analysis sub silentio of all evidence introduced at trial. We will not, however, circumscribe this discretion by burdening the court with the necessity of making an explicit determination for all expert testimony.”).


See, e.g., United States v. Green, 405 F. Supp. 2d 104 (D. Mass. 2005) (toolmark analysis); United States v. Mikos, No. 02-137, 2003 WL 22922197 (N.D. Ill. Dec. 9, 2003) (expert testimony relating to comparative bullet lead analysis); United States v. Horn, 185 F. Supp. 2d 530 (D. Md. 2002) (evidence of defendant’s performance on field sobriety tests); United States v. Rutherford, 104 F. Supp. 2d 1190 (D. Neb. 2000) (handwriting analysis).


See, e.g., United States v. Ford, 481 F.3d 215 (3d Cir. 2007); United States v. Moreland, 437 F.3d 424 (4th Cir. 2006); United States v. Brown, 415 F.3d 1257 (11th Cir. 2005); United States v. Davis, 397 F.3d 173 (3d Cir. 2005); United States v. Conn, 297 F.3d 548 (7th Cir. 2002); United States v. Havvard, 260 F.3d 597 (7th Cir. 2001); United States v. Malveaux, 208 F.3d 223 (9th Cir. 2000); United States v. Harris, 192 F.3d 580 (6th Cir. 1999).


In 2000, Michael Risinger published a study in which he found that, “as to proffers of asserted expert testimony, civil defendants win their Daubert reliability challenges to plaintiffs’ proffers most of the time, and that criminal defendants virtually always lose their reliability challenges to government proffers. And, when civil defendants’ proffers are challenged by

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