Criminal Procedure

Search and Seizure – Private Search Doctrine

State v. Gasper, 2026 WI 3 (filed Jan. 14, 2026)

HOLDING: The Fourth Amendment was not implicated in this case because the private search doctrine applied.

SUMMARY: Law enforcement officers obtained a warrant for Gasper’s cell phone after the National Center for Missing and Exploited Children (NCMEC) forwarded a CyberTipline report (which included a single, flagged, 16-second video) from Snapchat to the Wisconsin Department of Justice (DOJ). No person at Snapchat or NCMEC viewed the contents. Instead, Snapchat scanned its platform and identified the video file it flagged as known CSAM (child sexual abuse material) using a hash-based scanning program. [A hash value is a string of characters obtained by processing the contents of a given computer file and assigning a sequence of numbers and letters that correspond to the file’s contents (see ¶ 7 n.8).]

“The flagged video was first viewed by a person when an employee of the DOJ did so without a warrant. Then the CyberTip with the flagged video was forwarded to local law enforcement who also viewed the video without obtaining a warrant” (¶ 2).

Gasper (the defendant) was charged with 10 counts of possessing child pornography and nine counts of child exploitation based on the content on the cell phone. The defendant moved to suppress this evidence on the basis that it was obtained in violation of his Fourth Amendment rights. He relied entirely on the argument that the government exceeded Snapchat’s private search because a person in the government was the first to open and view the video and did so without a warrant (see ¶ 5).

The circuit court granted the motion to suppress. In a published opinion, the court of appeals reversed the circuit court. See 2024 WI App 72.

In a majority opinion authored by Justice Ziegler, the supreme court affirmed the court of appeals. It concluded that the private search doctrine applied in this case. “While the private search doctrine most often involves a person who has seen the evidence and then turns it over to law enforcement, the doctrine itself does not require that a person actually view the evidence. Whether a Snapchat employee viewed the video or not is of no moment to the private search doctrine, because the private search doctrine allows the government to review what a private actor has already searched, so long as there is a virtual certainty that its search will disclose nothing more of significance than what the private party search revealed” (¶ 40).

In concluding that the private search doctrine applied in this case, the majority indicated that “[i]t is undisputed that Snapchat performed a private search when it scanned and flagged the single, 16-second video as CSAM. The government did not exceed the scope of Snapchat’s search when it viewed the video because any expectation of privacy Gasper may have had in the video was frustrated by the private search, and there was virtual certainty that law enforcement would not find anything of significance beyond what the private search revealed. As a result, the Fourth Amendment is not implicated” (¶ 52).

Justice Ziegler, author of the majority opinion, also filed a concurrence. Justice Dallet filed a concurring opinion that was joined in part by Justice Crawford. Justice Hagedorn filed a concurring opinion that was joined by Chief Justice Karofsky and Justice Protasiewicz. Justice Crawford filed an opinion concurring in part and dissenting in part that was joined in part by Justice Dallet.