Admitting Computer "Thumbnail" Images Under The FRE

When "thumbnail" images are found on a computer, what can be inferred on whether the computer user was aware of their presence? The Fifth Circuit considered this issue in a recent conspiracy, terrorism and false statements trial in which "thumbnail" images of files found on the defendant's computer were admitted as probative evidence that the defendant had viewed and approved of such files; under the circumstances of the case, the issue concerned not the admissibility of the thumbnails but rather the weight to be given to the thumbnail evidence, in United States v. Mehanna, __ F.3d __ (1st Cir. Nov. 13, 2013) (No. 12–1461)

"Thumbnail" images are common features of computer displays and indices. Thumbnails are small images of pictures or other records that are often used to help the computer user recognize or organize computer files. Does the presence of a thumbnail image in a computer's hard drive or memory indicate that the user is aware of its presence, or of the contents of the computer file or link that the thumbnail may represent? The First Circuit noted that the presence of thumbnail images on a computer does not necessarily pose a question of admissibility, but rather it is likely one of weight in a case.

Allegedly Inflammatory Thumbnails?

In the case, defendant Mehanna was tried on a multi-count indictment arising from travel to Yemen in 2004 to find "a terrorist training camp." He was also charged with aiding terrorist activities on his return to the United States, by translating "Arab-language materials into English" and posting the information on a web site "that comprised an online community for those sympathetic" to alleged terrorist perspectives. Convicted by jury on all counts, the defendant appealed raising as one ground that the trial court had erroneously admitted "thumbnail images" from the computer. The defendant contended that the "'thumbnail' images retrieved from his computer" were unfairly prejudicial under FRE 403, and "that such images can exist on a person's computer without the person's involvement or knowledge." Mehanna, _ F.3d at _; see also First Circuit Assesses FRE 403 And The "Antiseptic" Trial (summarizing the facts of the case).

Weight Not Admissibility

The First Circuit devoted minimal attention to the issue of the admissibility of the thumbnail evidence. The defendant framed his challenge on unfair prejudice grounds under FRE 403. Instead, the circuit thought the issue was more appropriately focused "as an objection to the relevance of the evidence," under FRE 401), or "as an objection to the lack of proper foundation," under FRE 901. But even on the basis of these other rules, the use of thumbnails in this case posed no problems, despite the questions one might raise about the evidence. As the circuit explained:

In the end, it does not matter how we characterize this objection [in terms of relevancy, foundation or unfair prejudice]. Regardless, the objection goes to the weight of the evidence, not to its admissibility. One logical inference from the discovery of the thumbnails is that the defendant viewed and approved of such images. The government was free to argue in favor of this inference, and the defendant was free to argue otherwise. Jurors are not so naive that they must be shielded from choosing among reasonable but competing inferences extractable from proven facts.
Mehanna, __ F.3d at __.

The circuit dismissed further consideration of this issue as "pointless" and concluded that the defendant's "objection to the introduction of the thumbnails was appropriately overruled." Mehanna, __ F.3d at __ (citing United States v. El-Mezain, 664 F.3d 467, 509-10 (5th Cir. 2011) ("Evidence which tends to rebut a defendant's claim of innocent action is unlikely to be unduly prejudicial") (citing United States v. Duncan, 919 F.2d 981, 987–88 (5th Cir. 1990) (in prosecution for mail fraud testimony of forged signature on disability statement, which tended to rebut the claim that defendants had innocently filed insurance claims for genuine medical reasons, was not unfairly prejudicial); see also United States v. Hammoud, 381 F.3d 316, 342 (4th Cir. 2004) (holding that videotapes found in defendant's apartment depicting violence and anti-American sentiment were not unfairly prejudicial under FRE 403 in a prosecution for providing material support for a terrorist organization because they were probative of defendant's knowledge, “provided evidence of [his] motive in raising funds for Hizballah[,] and tended to contradict [his] claim that he sympathized only with the humanitarian goals of the organization”), overruled on other grounds by Hammoud v. United States, 543 U.S. 1097 (2005)).

Other Cases Considering The Use Of "Thumbnail" Images

In the digital world, thumbnail images are an extensively popular tool. Like the use of labels or file-names on a computer system, the thumbnail often serves the same reference function as does a term in a normal text index. Thumbnail files are frequently experienced today in visual search engines or image-organizing programs in which they serve as a key to opening or activating material obtainable to the activator. Some recent appellate cases noting the use of thumbnails include:

  • United States v. Glassgow, 682 F.3d 1107, 1110 (8th Cir. 2012) (No. 11-2611) (admitting pornographic thumbnail images from the defendant's computer that were in sketch form, which he alleged were not expandable for viewing so that prosecution's exhibits were only “similar” to the thumbnail pictures; however, a government's expert "verified that the images ... were the actual enlarged images from" the defendant's computer)
  • United States v. Nissen, 666 F.3d 486, 491 (8th Cir. 2012) (No. 10-3696) (in considering the defendant's sentence, noting: "Because the PSR [presentence report] explained that the thumbnail images were created when videos were edited or played in Windows Movie Maker, the court could have drawn the inference that Nissen knowingly possessed the videos because he viewed them or edited them at some point. Indeed, a court is permitted to rely on circumstantial evidence that demonstrates knowing possession of a certain number of images when deciding whether USSG § 2G2.2(b)(7)(D) applies.")
  • United States v. McNerney, 636 F.3d 772 (6th Cir. 2011) (No. 09–4011) (use under sentencing guidelines of thumbnails and assessing whether thumbnails are duplicate digital images or rather simply previews of digital images that are viewable without opening the digital folder in which the digital images are contained)
  • Perfect 10, Inc. v., Inc., 508 F.3d 1146, 1165 (9th Cir. 2007) (Nos. 06–55405, 06–55406, 06–55425, 06–55759, 06–55854, 06–55877) (in explaining the use and operation of thumbnail images, noting that an image may have been created originally to serve an entertainment, aesthetic, or informative function, but a search engine transforms the image into a pointer directing a user to a source of information" by transforming image into thumbnail which "shed[s] light on an earlier work, and, in the process, creat[s] a new one”))
  • Kelly v. Arriba Soft Corp, 336 F.3d 811, 815 (9th Cir. 2003) (No. 00-55521) (Defendant's "crawler downloads full-sized copies of the images onto Arriba's server. The program then uses these copies to generate smaller, lower-resolution thumbnails of the images. Once the thumbnails are created, the program deletes the full-sized originals from the server. Although a user could copy these thumbnails to his computer or disk, he cannot increase the resolution of the thumbnail; any enlargement would result in a loss of clarity of the image.")


One observation from the First Circuit's treatment of thumbnails in Mehanna was its rather routine consideration of the issue. Admissibility was not a barrier to consideration of the evidence. As the selection of sample cases above suggests, thumbnail evidence is being used in a number of contexts. While there might be a number of issues that can arise as a challenge to thumbnail image evidence, in the end it seems, rather than admissibility, the issue turns on the weight of the evidence.


Federal Rules of Evidence