By David Lundgren, Criminal Defense Lawyer at Lundgren & Johnson, PSC
In Lundgren & Johnson’s earlier video analysis of the Court of Appeals decision in State v. Contreras-Sanchez, I described geofence warrants as an investigative tool that can capture data from many devices, not just a suspect’s, and raised the concern that innocent people may be swept into serious criminal investigations. I also anticipated Minnesota Supreme Court review. That prediction proved correct.
The Minnesota Supreme Court has now issued its decision in State v. Contreras-Sanchez, 33 N.W.3d 700 (Minn. 2026). Although the Court did not ban geofence warrants across the board, it reversed the Court of Appeals on a critical constitutional issue and held that the warrant used in that case failed Minnesota’s particularity requirement.
A geofence warrant generally allows law enforcement to seek location-history data from a third party such as Google for devices that were present within a defined geographic area during a defined time period. As my prior analysis explained, that means many people’s devices can fall within the initial sweep even when those people have nothing to do with the crime.
In Contreras-Sanchez, investigators used a geofence warrant after a homicide victim’s body was found in a culvert in rural Dakota County. The warrant requested data for a 65-foot by 290-foot area from March 25 to April 26, 2021. After Google advised that processing the full month would overload its systems, officers requested data in two seven-day periods. The returns showed one device that appeared repeatedly at the culvert, including 46 data points over about 10 minutes. Officers then obtained additional path-of-travel data showing the device at a gas station before it entered the geofence, and later obtained identifying information linking the device to Ivan Contreras-Sanchez.
What the Court of Appeals Held
The Court of Appeals treated the case as a significant first-impression challenge to geofence warrants in Minnesota and upheld the warrant. It held that geofence warrants are not categorically forbidden as general warrants and must instead be evaluated case by case. It also concluded that this particular warrant was supported by probable cause, sufficiently particular, and not overbroad as to the anonymous data actually seized.
The Court of Appeals emphasized the rural location, the relatively small geofence, the anonymous nature of the first two steps, and the view that any officer discretion at step two was adequately constrained by the facts of the investigation. It therefore affirmed the denial of suppression and left the conviction in place.
That Court of Appeals reasoning is important because it framed geofence warrants as a tool that could be reasonable if narrowed by geography, time, and a step-by-step process. The court even assumed, without deciding, that Contreras-Sanchez had a reasonable expectation of privacy in the anonymous location data, but it still concluded the warrant passed constitutional muster. In short, the Court of Appeals saw the step-two expansion of the search as a limited and acceptable use of officer judgment rather than an unconstitutional delegation of discretion.
How the Minnesota Supreme Court Reversed the Court of Appeals
The Minnesota Supreme Court agreed with the Court of Appeals on some big-picture points, but it rejected the Court of Appeals opinion on the point that mattered most.
The Supreme Court held, first, that cell-phone users have a reasonable expectation of privacy in their location data stored by Google, so law enforcement conducts a search under Article I, Section 10 of the Minnesota Constitution when it accesses that data. Second, it held that geofence warrants are not categorically prohibited general warrants. Third, it held that the application in this case established probable cause. But fourth, and most importantly, it held that this warrant was insufficiently particular because it gave law enforcement unchecked discretion to decide which device IDs inside the geofence would be subjected to an additional search for more location information.
On that basis, the Supreme Court reversed and remanded.
That is the key reversal. The Court of Appeals had upheld the warrant’s step-two structure. The Minnesota Supreme Court did not. The Supreme Court explained that the problem was not the initial concept of a geofence warrant itself, nor the existence of probable cause to believe Google’s servers might contain evidence. The problem was that step two let officers decide for themselves which anonymous device IDs were “relevant” and then demand additional location history outside the geofence and outside the original narrow time-and-place limits, all without further judicial review.
In the Supreme Court’s view, that allowed impermissible exploratory rummaging through sensitive location data.
Just as significant, the Supreme Court took a stronger privacy view than the Court of Appeals. The Court of Appeals had assumed privacy without deciding it. The Supreme Court squarely held that cell-phone users have a reasonable expectation of privacy in location data collected and stored by Google under the Minnesota Constitution. It emphasized that this information can reveal deeply personal details about where a person goes and, by extension, intimate aspects of family life, religion, politics, health care, and other private associations.
The Court also rejected the idea that the third-party doctrine automatically defeats privacy protection simply because Google stores the data. And it was openly skeptical that supposedly anonymous geofence data is truly anonymous when law enforcement may be able to cross-reference that data to identify a person.
What the Supreme Court Did Not Do
For a criminal defense lawyer, it is just as important to recognize what the Minnesota Supreme Court did not do.
The Court did not declare all geofence warrants unconstitutional. In fact, it expressly agreed that geofence warrants are not per se invalid general warrants and relied on a hypothetical from the Court of Appeals showing how a very narrow geofence warrant might satisfy constitutional limits.
The Court also held that probable cause existed here and rejected the argument that the State needed individualized probable cause for every person whose device happened to fall within the geofence. So the Supreme Court did not shut the door on geofence warrants. Instead, it narrowed the constitutional path for using them in Minnesota.
The Court also did not hold that the 65-foot by 290-foot geofence or the March 25-to-April 26 timeframe was itself unconstitutional. It concluded those limits were sufficiently particular under the circumstances. The geographic area was tied to the culvert, the adjacent lightly traveled road, and the right-of-way ditch. The longer timeframe was justified because officers did not know exactly when the victim was killed or moved to the culvert. The constitutional defect was not the initial area or timeframe. The defect was step two of the warrant process.
That nuance matters. The new precedent is not “geofence warrants are illegal.” The new precedent is that Minnesota courts will treat access to Google-stored cell-phone location data as a constitutional search, will analyze these warrants under the Minnesota Constitution, and will require genuine limits on officer discretion when law enforcement tries to move from a narrow initial geofence to a broader search of additional location history.
That is a meaningful shift for any criminal defense lawyer litigating digital-search issues in Minnesota.
How Criminal Defense Lawyers Will Challenge Geofence Warrants Moving Forward
Moving forward, a criminal defense lawyer should be expected to challenge geofence warrants with a sharper focus on the exact language of the warrant and each step of the data-acquisition process.
After Contreras-Sanchez, the fight will often be whether the warrant required further judicial review, or otherwise contained clear and objective limits, before officers could expand the search beyond the original geofence and timeframe. The strongest arguments will focus on whether the “relevance” standard was too loose, whether the time-and-location limits actually held firm through later steps, and whether the supposedly anonymous data could realistically be re-identified.
The Supreme Court’s opinion gives criminal defense lawyers real openings to argue that anonymity alone does not cure the privacy problem. Location data may begin as a device ID, but the point of the investigation is often to turn that device ID into a person. That means courts will need to look carefully at how easily supposedly anonymous information can become identifying information.
The decision also shows that Article I, Section 10 of the Minnesota Constitution will be a central battlefield in future digital-search litigation. The Supreme Court expressly decided the case on independent state constitutional grounds and said it did not need to resolve the Fourth Amendment issue once it found a violation of Minnesota’s constitution.
For a criminal defense lawyer, that means state constitutional briefing is no longer optional in geofence cases. It should be front and center.
At the same time, lawyers should be careful not to overstate the holding. The Supreme Court did not decide that a new warrant is automatically required at every stage of every geofence investigation. The Court held that this warrant lacked sufficient particularity because step two gave officers unfettered discretion and no judicial review before the expanded search. The Court expressly left open whether clear instructions in the original warrant could ever sufficiently limit officer discretion, or whether an additional warrant is required at each stage where law enforcement seeks more location data.
That unresolved issue is likely to become one of the next major fights.
Why Preservation Matters After Contreras-Sanchez
Preservation is going to matter enormously.
Even though the Minnesota Supreme Court found a constitutional defect, it did not finish the suppression analysis. Because the Court of Appeals had upheld the warrant, it never reached the State’s fallback arguments about the good-faith exception and harmless error. The Supreme Court therefore remanded for the Court of Appeals to address those issues.
That means the case now stands as a reminder that suppression litigation in geofence cases is not just about whether the warrant was valid in the abstract. It is also about preserving remedy issues, fruit-of-the-poisonous-tree arguments, and objections to later investigative steps that depend on the original data seizure.
For that reason, a criminal defense lawyer handling a geofence case should build the record at every stage. Counsel should identify whether the warrant application differs from the warrant actually signed, whether officers obtained further data without a new warrant, whether later warrants depended on information produced by earlier questionable steps, and whether the State is likely to fall back on good faith or harmless error if a constitutional problem is found.
Counsel should also compare the application, proposed warrant, signed warrant, and actual execution of the warrant. In Contreras-Sanchez, the application and warrant language differed on step three. The application said officers would seek a second warrant before obtaining subscriber information, but the signed warrant language did not require that. In practice, officers ultimately did apply for a second warrant before Google disclosed identifying subscriber information.
That detail matters. It shows why lawyers should not assume that the application, proposed warrant, signed warrant, and execution all line up. In digital-search cases, small differences in language can become major constitutional issues.
Contreras-Sanchez shows that those issues are not secondary. They may determine whether a constitutional win turns into meaningful relief.
Conclusion
My earlier analysis of the Court of Appeals decision focused on the privacy risks geofence warrants pose for innocent people and the danger of overreach in an era of constant digital tracking. The Minnesota Supreme Court’s new opinion validates those concerns in an important way.
The Court did not ban geofence warrants outright. But it did reverse the Court of Appeals and make clear that Minnesota’s Constitution places real limits on how far law enforcement may go once it gains access to Google-stored cell-phone location data.
For a criminal defense lawyer, that is the takeaway: geofence warrants remain in play, but privacy, particularity, and discretion will now define the fight.
This article is not legal advice. It is meant for educational purposes only. If you have a legal issue, contact a knowledgeable criminal defense lawyer to discuss how the law applies to your case.