United States v. Loren Copp, 1 F.4th 573

Loren A. Copp was convicted of producing/attempting to produce child pornography (18 U.S.C. § 2251), possessing child pornography (18 U.S.C. § 2252A), and related interstate-enticing/transmitting offenses; district court sentenced him to 780 months.
Federal agents seized hundreds of pornographic photos/videos from Copp’s home, including images showing a man’s naked torso, hands, feet, and genitals abusing a child.
Before trial the government sought photographs of Copp’s hands, feet, abdomen, and genitals to compare with seized images; the district court allowed everything except photos of Copp’s genitals.
On the fifth day of a bench trial, Copp sought permission to photograph and display photos of his penis (claiming an identifying birthmark) and to call a former cellmate to testify about the mark; the court denied both requests.
The district court excluded the evidence on two independent bases: (1) lack of probative value (photos/testimony taken years later were unlikely to prove appearance at the time of the videos and would cause undue delay/prejudice), and (2) as a discovery sanction for Copp’s late disclosure and previous refusal to permit genital photographs.
The Eighth Circuit affirmed, applying abuse-of-discretion review for evidentiary exclusions (with de novo review for constitutional-right claims) and finding any error harmless given overwhelming evidence supporting the convictions.

Issue	Copp's Argument	Government's Argument	Held
Whether Copp could photograph and display photos of his penis at trial	Photos would show an identifying birthmark proving he was not the man in the pornographic images	Photos taken years later had little probative value, would prejudice/unduly delay the trial, and were untimely disclosed	Denied; exclusion affirmed for lack of probative value and as a discovery sanction; any error harmless
Whether Copp could call a former cellmate to testify about the birthmark	Cellmate’s testimony would identify the birthmark and exculpate Copp	Testimony lacked probative value (remote in time), prejudicial/delaying, and was untimely disclosed	Denied; exclusion affirmed for lack of probative value and as discovery sanction; any error harmless

United States v. Condon, 720 F.3d 748 (8th Cir. 2013) (deference to district court evidentiary rulings)
United States v. West, 829 F.3d 1013 (8th Cir. 2016) (de novo review when exclusion implicates constitutional rights)
United States v. Davis, 244 F.3d 666 (8th Cir. 2001) (prejudice from late evidence can be inferred)
United States v. Bass, 794 F.2d 1305 (8th Cir. 1986) (trial court balances probative value against prejudicial effect)
United States v. Sims, 776 F.3d 583 (8th Cir. 2015) (broad discretion to sanction discovery violations)
Taylor v. Illinois, 484 U.S. 400 (1988) (exclusion is permissible sanction for willful discovery violations)
Anderson v. Groose, 106 F.3d 242 (8th Cir. 1997) (willful discovery violations for tactical advantage justify exclusion)
United States v. Clay, 883 F.3d 1056 (8th Cir. 2018) (defendant must have adequate opportunity to lay foundation for defense evidence)
United States v. Yarrington, 634 F.3d 440 (8th Cir. 2011) (harmless-error standard)
United States v. Willins, 992 F.3d 723 (8th Cir. 2021) (overwhelming evidence supports affirmance)
United States v. Herbst, 668 F.3d 580 (8th Cir. 2012) (victim testimony and substantial digital evidence can support convictions)