When a Hash Match Counts as a Private Search
Google was the provider: the company operating the email service. A hash is a digital fingerprint generated from a file's underlying data. In Google's process, a person first reviewed a reference file and classified it as child sexual abuse material, or CSAM. When a file in Richard Brillhart's Gmail account produced the same hash, Google sent the file and a CyberTip to the National Center for Missing and Exploited Children, which forwarded the material to police.1
An officer opened the reported file without a warrant. The Eleventh Circuit held that this review did not exceed Google's earlier private search because the record established an exact match to a reference file previously reviewed by a person. The decision placed the Fifth, Sixth, and Eleventh Circuits on one side of a 3-3 split, with the Second, Fourth, and Ninth Circuits on the other.1
Yahoo and Google independently flagged email accounts tied to Brillhart. Yahoo reported 241 files after human review. Google found four files across three accounts: three were reviewed by a person, and one was identified through Google's hash-matching protocol.1
NCMEC forwarded the files and identifying information to Fort Myers police. Officer Katrina Lee understood that Google's hash-matched file corresponded to a reference file reviewed in the past. Without first obtaining a warrant, she opened the reported files and then relayed her findings to Homeland Security Investigations.1
After obtaining warrants for Brillhart's apartment, car, and accounts, federal agents searched his residence. A micro-SD card in his bedroom contained 40 videos and 60 images of CSAM. Six images matched files previously sent through a Yahoo account tied to him.1
Brillhart moved to suppress the evidence from his Google account. The district court denied the motion on three alternative grounds: no reasonable expectation of privacy, the private-search doctrine, and good faith. A jury later convicted him of distribution and possession, and the court imposed a 480-month sentence.1
The Eleventh Circuit affirmed the suppression ruling and the convictions. It held that Google's protocol qualified as a private search and that the officer learned no materially new information by opening the same file. The court separately vacated a sentencing enhancement and remanded for resentencing.1
Repeated Review and Occupational Exposure
This issue is separate from the Fourth Amendment question. Brillhart did not address investigator health or evaluate hash matching as a workplace intervention. The occupational literature nevertheless provides context for agencies whose personnel repeatedly review CSAM.
Occupational research
Studies of investigators and law-enforcement staff who review disturbing material report associations with secondary traumatic stress, burnout, sleep disruption, and related reactions in some workers. The reported effects are not uniform, and personnel may also describe professional efficacy and meaning in the work.78
Across the studies, peer, social, and organizational support are associated with better reported outcomes. More frequent exposure, low support, and feeling overwhelmed are associated with worse ones.8910
The studies reviewed here did not test hash matching as a mental-health intervention. They describe occupational exposure and workplace conditions; they do not establish that an exact-match system prevents trauma.
Appendix A — Case Authorities
The six published appellate decisions shown in the circuit graphic. Pinpoints identify the portions supporting the case account and the private-search divide.
1. United States v. Brillhart, Nos. 24-13226 & 24-13232, official opinion at PDF pp. 3–10, 16–27, 36–37 (11th Cir. July 9, 2026). Pages 3–10 supply the provider process, investigation, suppression posture, trial, and sentence; pages 16–27 address the split and hold that Google's protocol qualified as a private search; pages 36–37 state the sentencing and appellate disposition.
2. United States v. Reddick, 900 F.3d 636, 637–40 (5th Cir. 2018). The Fifth Circuit held that police learned nothing beyond the private hash-based search when they opened the reported files.
3. United States v. Miller, 982 F.3d 412, 418–20, 427–31 (6th Cir. 2020). The Sixth Circuit treated Microsoft's automated matching and reporting as private conduct and held that the later police review did not exceed that search.
4. United States v. Maher, 120 F.4th 297, 314–19 (2d Cir. 2024). The Second Circuit held that a Google hash match did not authorize police to open the unreviewed file without a warrant, although good faith prevented suppression.
5. United States v. Lowers, 170 F.4th 134, 148–56 (4th Cir. 2026). The Fourth Circuit held that police exceeded the private search when they opened files that neither Google nor NCMEC had viewed; it affirmed on attenuation grounds.
6. United States v. Wilson, 13 F.4th 961, 971–77 (9th Cir. 2021). The Ninth Circuit held that opening four files Google had reported through automated matching exceeded the provider's private search.
Appendix B — Occupational Research
The studies describe reported experiences and associations among personnel exposed to disturbing material. They do not evaluate hash matching as an intervention.
7. Lisa M. Perez et al., “Secondary Traumatic Stress and Burnout among Law Enforcement Investigators Exposed to Disturbing Media Images”, 25 Journal of Police and Criminal Psychology 113–124 (2010). Cross-sectional self-report study of 28 federal personnel.
8. Patrick Q. Brady, “Crimes Against Caring”, 32 Journal of Police and Criminal Psychology 305–318 (2017). Observational study of 433 Internet Crimes Against Children Task Force personnel.
9. Nicolai Johannes Kleineidam & Andrea Fischbach, “Feeling with the Victim”, 41 Journal of Police and Criminal Psychology 308–318 (2026). Cross-sectional online study of 168 investigators examining reported reactions and working conditions.
10. Fazeelat Duran & Jessica Woodhams, “Ongoing Exposure to Distressing Material Is Associated with Worsening Mental Health in UK Law Enforcement Staff” (2026). Qualitative study of 21 staff members based on 63 interviews.