CA6: Looking at hash values on images of CP didn’t expand the private search

Officers looking at the hash information on child pornography images sent from NCMEC who got them from gmail wasn’t expansion of the private search under Jacobsen and Walter. United States v. Miller, 2020 U.S. App. LEXIS 37787 (6th Cir. Dec. 3, 2020):

Applying this test, we must ask whether Google’s hash-value search of the files using its digital eyes made it virtually certain that Detective Schihl would discover no more than what Google had learned when he viewed the images with his human eyes. Jacobsen, 466 U.S. at 119. We are helped in this endeavor by two thoughtful decisions applying the private-search doctrine in this new context. Reddick, 900 F.3d at 638-39; Ackerman, 831 F.3d at 1305-07.

In Ackerman, AOL matched one image in the defendant’s email with a child-pornography hash value. AOL sent the email and its four images to NCMEC. 831 F.3d at 1294. An NCMEC analyst viewed the email and images. Id. In an opinion by then-Judge Gorsuch, the Tenth Circuit held that NCMEC’s search exceeded the scope of AOL’s search. Id. at 1305-06. AOL learned only that a single image had a hash-value match, but the NCMEC analyst viewed the entire email. Id. The analyst’s search thus disclosed a lot more information: whether the other images were child pornography and whether the email contained correspondence. Id. Yet Ackerman reserved whether its holding would change if the analyst had viewed only the one image. Id. at 1306.

In Reddick, the Fifth Circuit considered this reserved question. There, the defendant loaded images into a Microsoft account with hash values matching child pornography. 900 F.3d at 637-38. Microsoft sent the images to NCMEC, which shared them with a detective. Id. at 638. The court held that the detective’s viewing did not exceed the scope of Microsoft’s search. Id. at 639. It gave two reasons. Microsoft’s hash-value matching allowed it to identify child pornography “with almost absolute certainty[.]” Id. (citation omitted). And the detective’s viewing “was akin to the government agents’ decision to conduct chemical tests on the white powder in Jacobsen.” Id.