COA issues first impression decision on constitutionality of warrant to search contents of smartphone, holds “the warrant must specify the particular items of evidence to be searched for and seized from the [smart]phone,” and its authorization must be “limited to the time period and information or other data for which probable cause has been properly established… in the warrant’s supporting affidavit”
State v. Emil L. Melssen, 2024AP1942-CR, 11/20/25, District IV (recommended for publication); case activity (including briefs)
Emil Melssen appeals from a judgment of conviction following a jury trial, in which he was convicted of possession of methamphetamine with intent to deliver and related charges. He argues that the evidence was insufficient to sustain his conviction and the circuit court erroneously denied his motion to suppress evidence obtained in the execution of two search warrants. COA rejects Melssen’s sufficiency argument, but concludes that the warrant to search his smartphone violated the Fourth Amendment because it was overbroad and not carefully tailored to its justifications. The court remands for a determination on the remedy.
This case arose after police investigated a physical altercation between Melssen and “YZ” outside YZ’s girlfriend’s residence. (¶5). The girlfriend, “AB,” reported that YZ stabbed Melssen. During the investigation, police began to suspect that Melssen was the aggressor and shifted their focus to whether he had committed a battery. (¶6). Before the confrontation, AB had told Melssen that YZ had physically assaulted her the night before.
Melssen and AB both told police that they had been communicating prior to and after the altercation. (¶7). When police interviewed YZ, he told them Melssen had attacked him, Melssen and AB regularly communicated by smartphone, and were “constantly communicating about drugs and refer to drugs as ‘groceries.’” (¶8). Police seized Melssen’s phone and applied for a warrant to search it. As part of the warrant application, a detective swore to an affidavit that purportedly established probable cause that evidence related to “battery, domestic abuse incidents, and/or narcotic activity” would be found on the smartphone.
The affidavit included detailed factual averments about the police investigation into the altercation between Melssen and YZ. By contrast, there were limited averments that could support a finding that anything of evidentiary value would be located on Melssen’s smartphone. (¶¶9-10). The circuit court issued the warrant authorizing police to search what appears to be nearly the entirety of the phone’s data. (¶11). Police found incriminating text messages between Melssen and two individuals, which could support the reasonable inference that Melssen was involved in the distribution of controlled substances. (¶12). Police then applied for and obtained a second warrant to search Melssen’s home that relied primarily on the incriminating texts. (¶13). In his home, they found methamphetamine, drug paraphernalia, and other items consistent with drug distribution. (¶14).
The state charged Melssen with possession with intent to deliver methamphetamine in an amount over ten grams; maintaining a drug trafficking place; and possession of drug paraphernalia. Prior to trial, Melssen moved to suppress the evidence obtained in the two searches on the basis that the warrant application did not establish probable cause to believe that his phone contained evidence related to the incident with YZ or narcotic activity. (¶¶15-16). Regarding “narcotic activity,” Melssen pointed out that the only relevant facts were the detective’s averment that he knew AB to be a drug user and that drug sales had taken place at her residence, and YZ’s assertion that Melssen and AB communicated about drugs. (¶16). The circuit court denied Melssen’s motion and the case proceeded to trial. (¶¶20-21).
As the focus of the opinion is the constitutionality of the search warrant for the phone, we will not the sufficiency argument other than to note that COA concludes there was sufficient evidence to sustain the convictions. (¶¶25-30).
Next, COA turns to Melssen’s challenge to the search warrant for his phone. COA explains that the “Warrant Clause” of the US Constitution sets forth two related requirements—probable cause and particularity—, both of which are relevant to this appeal. The warrant application must appraise the judge of sufficient facts to support the belief that “there is a fair probability that contraband or evidence of a crime will be found in a particular place.” State v. Ward, 2000 WI 3, ¶23, 231 Wis. 2d 723, 604 N.W.2d 517 (citing Illinois v. Gates, 462 U.S. 213, 238 (1983)). A warrant must “particularly” describe the place to be searched and the items to be seized, and must be limited to only those “specific areas and things for which there is probable cause to search.” See Maryland v. Garrison, 480 U.S. 79, 84 (1987). (¶¶32-34).
There are no United States Supreme Court cases, and no published Wisconsin cases, that have addressed what the dual mandates of the Warrant Clause require of an application for a warrant to search the contents of a smartphone. (¶36). Although it does not directly apply the probable cause and particularity requirements, COA relies on Riley v. California, 573 U.S. 373 (2014), in which the Court determined that searches of smartphones must be authorized by a warrant. (¶37). The concern about indiscriminate searches of residences by government actors is at the core of the Fourth Amendment, and the Riley Court observed that smartphones contain personal and sensitive information far beyond what would be found in a residence “in any form.” (¶39). COA reasons that given the “capacities of smartphones and their ubiquitous use in managing and recording many aspects of modern life, it is easy to imagine how an unlimited search of a person’s smartphone would reveal private details of the person’s life that are wholly unrelated to any criminal investigation that justified the search.” (¶40). Thus, COA concludes:
For all of these reasons, we do not agree with the circuit court’s conclusion that, to the extent there is probable cause that evidence of a crime will be found on a smartphone, this necessarily means that there is probable cause for an essentially unrestricted search of the smartphone’s contents. Given the storage capacities and the routine and frequent uses of smartphones, adoption of that conclusion would amount to a judicial greenlight for precisely the kind of invasive governmental conduct that the Fourth Amendment was designed to prevent. See Garrison, 480 U.S. at 84; State v. Noll, 116 Wis. 2d 443, 450-51, 343 N.W.2d 391 (1984).
Under the circumstances, we join several other state and federal jurisdictions in emphasizing that, like other warrants, a warrant to search a smartphone must be “carefully tailored to its justifications.” See Garrison, 480 U.S. at 84 (addressing warrants in other contexts). It is not sufficient for the warrant application to establish that there is probable cause to believe that there is a fair probability that the smartphone contains some evidence of a crime. See Burns, 235 A.3d at 773. “Just as probable cause to believe that a stolen lawnmower may be found in a garage” does not entitle police to search an “upstairs bedroom,” Garrison, 480 U.S. at 84-85, probable cause to believe that a certain kind of evidence (such as text messages and other digital communications) will be found on the smartphone does not necessarily justify searching other types of data on the smartphone (such as internet browsing history or digital documents of other types).
(¶¶41-42). Thus, COA holds that “the warrant must specify the particular items of evidence to be searched for and seized from the [smart]phone,” and its authorization must be “limited to the time period and information or other data for which probable cause has been properly established through the facts and circumstances set forth under oath in the warrant’s supporting affidavit.”
Turning to the warrant application in this case, COA concludes that the majority of the averments were about the battery of YZ, and that there was a fair probability that evidence related to the battery would be found on the phone. (¶¶44-47). However, there was only probable cause to believe that evidence related to the battery would be found in the call log from the specific day, and in other communications on the phone during the time period directly following the altercation, when Melssen was “repeatedly texting from the ambulance and the hospital.” But the warrant authorized police to conduct a much broader search. Accordingly, the warrant is overbroad as to the authorization to search for evidence related to battery because it is not carefully tailored to its justifications. (¶49).
Next, COA concludes that the warrant application lacked the probable cause necessary to search for evidence of “narcotic activity.” (¶50). The averments in the warrant application were “exceptionally vague and exceedingly slim” as they were limited to: (1) YZ’s uncorroborated statement that AB and Melssen are “constantly communicating about drugs and refer to drugs as ‘groceries.’” and (2) a detective’s averment that he was aware that AB was a “drug user” and that “sales of methamphetamine” had taken place at AB’s residence. Even drawing all reasonable inferences in favor of the warrant-issuing judge’s determination, these facts are “clearly insufficient” to establish probable cause that evidence of a drug-related crime would be found on Melssen’s smartphone. (¶51). Only YZ’s vague statement connects the phone to drugs, but COA points out that it is not a crime to communicate about drugs. (¶52). The court also concludes that even if these averments “were marginally adequate to establish probable cause that evidence of drug possession would be found on the smartphone,” they would not broaden the search much beyond what it previously outlined, as the only communications referenced were between Melssen and AB. (¶54). Thus, the warrant authorized a far more extensive search than was allowed by the Warrant Clause’s dual mandates of probable cause and particularity, and Melssen’s rights were violated by the search. (¶55).
COA then considers the remedy, concluding that the record is insufficient to address the state’s preserved arguments about the applicability of the plain view doctrine and the good faith exception. (¶¶56-60). Finally, COA addresses the subsequent search warrant for Melssen’s residence. COA concludes that because it does not determine whether the text messages should be suppressed, it also does not determine whether they could be used as probable cause to support the residence warrant and directs the circuit court to, on remand, address how its conclusion on the smartphone evidence affects the validity of the warrant for the residence and any other related issue. (¶¶61-63).