9th Circuit creates private search exception circuit split

In recent years, child pornography criminal prosecutions have been on the rise in both state and federal courts nationally. The cases often start with a tip to law enforcement from search engines, peer-to-peer networks, or other social media platforms. As a result, a search warrant is executed at an individual's home and office, resulting in government agents seizing the illegal images and videos, which leads to the filing of felony charges. Punishment for this conduct is severe and includes prison time, and public registration for life as a sex offender.

In the case of United States v. Wilson, 18-50440 (9th Cir. Sep. 21, 2021), the 9th Circuit found the private search exception to the Fourth Amendment inapplicable, and therefore that the constitution's protection against unreasonable search and seizure was violated, where a search warrant was predicated on National Center for Missing and Exploited Children tip to law enforcement regarding the defendant's possession of child pornography. The investigation into Wilson's online activity was triggered when Google, as required by federal law, reported to NCMEC that Wilson had uploaded four images of apparent child pornography to his email account as email attachments.

The case would ultimately turn on the fact that no one at Google had opened or viewed Wilson's email attachments. Rather, an automated process called "hash matching" was utilized. This system identifies the unique "hash value" of an image -- essentially a long series of numbers and letters similar to a fingerprint for an image file -- and then compares it to a database of hash values previously deemed by the company to constitute child pornography. After receiving Google's report, an employee at NCMEC then, also without opening or viewing the images themselves, sent Wilson's email attachments to law enforcement, where an officer ultimately viewed the email attachments without a warrant. The officer then applied for warrants to search both Wilson's email account and Wilson's home, describing the contents of the attachments in the probable cause affidavit to the warrant application.

To analyze the Fourth Amendment implications of the viewing of the image files without a warrant, the 9th Circuit first reviewed the leading precedents which outline the contours of the private search doctrine. The Fourth Amendment protects individuals from government actors, not private ones. Burdeau v. McDowell, 256 U.S. 465 (1921). Federal courts have addressed the situation in which a private party searches the defendant's person or property in a way which would have violated the Fourth Amendment had the search been conducted by a state actor. Under the "private search doctrine," if private parties provide evidence to the government "on [their] own accord[,] ... it [i]s not incumbent on the police to ... avert their eyes." Coolidge v. New Hampshire, 403 U.S. 443, 489 (1971).

Walter v. United States, 447 U.S. 649 (1980), concerned the mistaken delivery of a box of obscene films to an incorrect recipient who, upon opening the box and examining the suggestive materials and explicit descriptions on the individual film boxes within, notified the FBI. The FBI seized the boxes and screened one of the films before obtaining a warrant. In finding that the viewing of the films by law enforcement constituted a Fourth Amendment violation, the Supreme Court relied on several factors. First, it was "perfectly obvious," in the court's words, that the agents' reason for viewing the films was to determine whether a crime had occurred. The labels may have provided probable cause, but a further inspection was necessary to obtain the evidence which was later used at trial. Second, the FBI had expanded the scope of the search which the private actor had undertaken because the individual to whom the package was mistakenly delivered had not actually viewed the films. The court reasoned that while the private search had violated Walter's privacy to some degree, the viewing of the films constituted a further intrusion not accomplished by the initial private search. Notably, the dissenting justices in Walter would have found no Fourth Amendment violation because, in their view, the contents of the containers were so obvious based on the labels that viewing the films did not tell law enforcement anything material which they did not already know from simply reading the labels.

Several years later, United States v. Jacobsen, 466 U.S. 109 (1984), addressed the subsequent government search of a FedEx package which had been partially opened by FedEx employees. While examining a damaged package, the FedEx employees opened the package, cut open a tube within the package, and found a series of four zip-lock plastic bags, the outermost enclosing the other three and the innermost containing white powder. The employees did not open the innermost bag, but rather packaged it back up and called the DEA. The DEA agents who responded visually inspected the bags by removing them from the tube and then each bag, removing a sample of powder and testing it using a field chemical test, which confirmed the powder was cocaine. The Supreme Court considered both the degree to which the government obtained new information from its subsequent search and the extent to which the government's investigation intruded on the defendant's privacy interests to a greater degree than had the FedEx employees.

Jacobsen allowed the government to "reexamine," the package in the same manner as the FedEx employees had already done, and to utilize the employees' testimony about their observations. The Supreme Court ultimately concluded that removal of the plastic bags and their visual inspection by the agents did not create any additional intrusion as the employees had already done the same, and had left the package unsealed for the agents to examine. Critically, when discussing the field chemical test, the court found that the scope of the private search had been expanded by the agents as the FedEx employees had not employed any such test. Nevertheless, the chemical test did not violate the Fourth Amendment as the court found that Jacobsen had no legitimate expectation of privacy in the chemical composition of the powder.

In assessing the warrantless viewing of the images by law enforcement in Wilson, the 9th Circuit made two critical holdings based on Walter and Jacobsen: First, the government search exceeded the scope of the private search because it allowed the government to learn new, critical information that it relied on in the warrant application and at trial. Second, the government search also expanded the scope of the private search because the government agent viewed Wilson's email attachments even though no private party had done so, thereby creating a further intrusion in Wilson's privacy.

Several arguments raised by the government, and rejected by the 9th Circuit, are worth noting. First, the government argued that the law enforcement review of the images allowed the government to learn nothing new, because Google had already classified the images as child pornography through hash matching. The 9th Circuit rejected this point, noting that no one at Google could have described with specificity was the images actually depicted, but rather simply that they had hash values which had previously been categorized as contraband images. The "gulf," in the 0th Circuit's words, between what Google knew about the images' contents and how the agent, having viewed the images himself, described them in his warrant application was striking. The hash matching categorization, the court found, provided even less information to law enforcement on its face than the video labels had in Walter.

Second, regarding the degree of invasion of Wilson's privacy, the 9th Circuit rejected the government's contention that Wilson's expectation of privacy had already been frustrated when Google scanned the images using its hash matching technology. Recalling the chemical field test in Jacobsen, the court concluded that the "critical fact" is that no Google employee viewed Wilson's files before the law enforcement agent did. Just as in Jacobsen, where the chemical test expanded the scope of the search beyond what the FedEx employees had done, so too had the agent's viewing of the images expanded the scope of the search. For this reason, the 9th Circuit distinguished its prior holding in United States v. Tosti, 733 F.3d 816 (9th Cir. 2013), in which a private party showed law enforcement thumbnails of images found on the defendant's laptop which appeared to be child pornography. Neither enlarging the thumbnails nor scrolling through the folder containing the images expanded the scope of the prior private search because the police learned nothing new through their actions.

Finally, the 9th Circuit, noting a growing circuit split in this area, addressed the analysis of the 5th and 6th Circuits, which have reached the contrary result and upheld similar government searches based on NCMEC hash-matching tips. The 5th Circuit in United States v. Reddick, 900 F.3d 636 (5th Cir. 2018), held that the subsequent visual review of the hash-matched images was analogous to the chemical field test in Jacobsen, finding that opening the files merely confirmed what law enforcement already knew through the private search. As the 9th Circuit explained, that analysis conflates Jacobsen's private search doctrine holding with its separate holding about drug field tests. Drug field tests do not trigger the Fourth Amendment in any circumstance, whether preceded by a private search or not, whereas drug laboratory tests, which provide significantly more information, do. The 9th Circuit found opening the images to be much more analogous to a drug laboratory test, which provides extensive details about the chemical composition of the substance in question, similar to the extensive details about the contents of the images viewed by the agent in Wilson.

The 6th Circuit similarly found the 5th Circuit's analogy to a drug field test wanting, but upheld a similar search on different grounds in United States v. Miller, 982 F.3d 412 (6th Cir. 2020). The 6th Circuit focused on the technological reliability of the hash matching itself and, in the 9th Circuit's view, impermissibly shifted the burden to the defendant to demonstrate that the hash match was unreliable in order to show a Fourth Amendment violation. The 9th Circuit held that the reliability of the hash matching procedure may well create probable cause sufficient to obtain a warrant on the basis of a NCMEC tip, but cannot obviate the need for a warrant prior to executing a warrantless search by opening the image files to confirm their contents.

NCMEC tips predicated on private electronic service provider hash matching are a common feature in both state and federal child pornography prosecutions. Wilson creates a new avenue of attack for defendants whose electronic files were viewed by law enforcement prior to obtaining a warrant.

Our law firm has a subspecialty in defending child pornography cases in state and federal courts. We are re-reviewing the probable cause declarations in search warrant cases to determine whether the Wilson holding applies. Given the importance of the issue and the growing circuit split, one would expect the Supreme Court to take up a private search doctrine case in the near future to clarify the application of Walter and Jacobsen to the new technologies utilized in the age of internet crime investigations.