County police officers were investigating a theft of farm equipment. They applied for a “geofence warrant” to be served on Google:

“A geofence warrant authorizes the seizure of location data collected from smartphones of individuals within a particular area over a specified range of time.” United States v. Rhine, 652 F. Supp. 3d 38, 66 (D.D.C. 2023). It “seeks cell phone location data stored by third-party companies like Google, which offers the Android operating system on which millions of smart phones run and offers other applications commonly used on phones running on other operating systems.” Id. at 66-67. Because “[t]he scope of location data captured by a geofence is limited by geographic and temporal parameters,” “geofence warrants identify the physical area and the time range in which there is probable cause to believe that criminal activity occurred.” Id. at 67. “Unlike a warrant authorizing surveillance of a known suspect, geofencing is a technique law enforcement has increasingly utilized when the crime location is known but the identities of suspects is not.”

Tomanek v. State, 261 Md. App. 694, 703 (2024).

The Tomanek Court explained that: “The purpose of the warrant was to ascertain if any such [mobile] device was in the area of the Frederick Road property between April 3 and April 11, 2020, when the theft was believed to have occurred. The court granted the warrant application, and a search warrant was served on Google.”

Google responded that nine different devices had shown activity within 100 meters of the property during the time range specified. Only one of them showed activity around the property on multiple dates and for extended periods of time.

Google identified the owner as Tomanek. Police surveillance observed a tractor matching the description of the stolen one on his property. They obtained a search warrant. During the execution of it, Tomanek shot at them. A subsequent search found property that appeared to be stolen.

Tomanek challenged the geofence warrant as an illegal “general warrant” that lacked sufficient particularity and probable cause. He moved to suppress the fruits and made related arguments as to the shooting.

On April 4, 2020, a witness observed the stolen farm equipment on the farm. On April 11, a witness found it missing. Another witness saw an antique tractor being hauled away between April 3 and 5. The police affidavit stated:

Based on that information, the affiant requested permission to search Google’s business records for “anonymized DeviceID data” of cell phone users that reported a location within a 100-meter radius of the main residence of the [victim’s] Frederick Road property between April 3 and April 11, 2020.

The warrant provided the latitude and longitude of the victim’s property.

The application noted that “anonymized DeviceID data does not contain personal identifying information about the end user,” and that a second warrant “would be needed to access any personal identifying information related to an account.”

The affidavit in support of the warrant stated in part:

Google collects and retains location data from Android-enabled mobile devices when a Google account user has enabled Google location services.

Another warrant explained:

According to the warrant’s affiant, due to the amount of equipment taken from the Frederick Road property, it was “very likely” that the perpetrator had taken multiple trips to the property during the time frame between April 3 and April 11, 2020. The affiant noted that Google had responded to the geofence warrant in December 2020, and, in so doing, had provided nine different Device IDs that showed potential activity within the area and time frame set forth in the geofence warrant. Upon reviewing that information, the affiant noted that only one of those nine devices was “located on and around the victim’s property on multiple dates for extended periods of time consistent with the timeframe of the burglary.”

Google later provided the subscriber information for that device.

Tomanek’s first argument is that the geofence warrant was an invalid “general warrant” that lacked sufficient particularity and probable cause. Tomanek contends that there was nothing in the warrant application to identify a particular suspect or to connect the crime to the use of any particular technology. Tomanek also contends that the warrant application was too broad in terms of the time period—approximately one week—over which the police were permitted to search. Tomanek argues that the warrant application constituted the sort of “general exploratory rummaging” that courts have consistently found to be a violation of the Fourth Amendment.

The Court rejected the challenge.

Regarding probable cause, the warrant application established the following relevant facts: that the Frederick Road property was a vacant, twelve-acre farm in a rural area; that, on April 11, 2020, farm equipment and other items had been reported missing from the Frederick Road property; that a family member had gone to the property on April 4, 2020, and observed that the missing items were still there; that the property owner had gone to the property on April 11, 2020, and observed that the missing items had been taken; that the property was private and had “no trespassing” signs posted; and that a witness had observed an unidentified individual hauling a piece of farm equipment away from the property at some point between April 3 and April 5, 2020. The warrant application also established that Google stored identifying information, including names and addresses, of Google account holders; that Google also collected historical location data on Google account holders via the account holder’s mobile device; that such data was likely to reveal the geographic location of the account user at a particular time; and that, if such data showed that a mobile device was in the area of the Frederick Road property during the relevant time frame, Google would likely have a name and address associated with that device. From those facts, a fair probability existed that a crime—the theft of the farm equipment—had taken place at the Frederick Road property at some point between April 3 and April 11, 2020. In addition, a fair probability existed that Google would have location data and identifying information for the perpetrator or perpetrators. As such, the issuing judge had a substantial basis for concluding that a search of Google’s records would uncover evidence of a crime.

As to the warrant’s particularity, the scope of the search—location data for mobile devices that showed activity within a 100-meter radius of the main residence of the Frederick Road property between April 3 and April 11, 2020—was precise and was in no sense “overbroad” or “wide-ranging” when considered in conjunction with the circumstances of the crime. As noted, the police had probable cause to believe that farm equipment was stolen from the Frederick Road property at some point during that time period, and the police had probable cause to believe that the perpetrator’s identity was stored in Google’s records via his location data. The search parameters were therefore carefully tailored to the search’s justifications.

Moreover, the property was a vacant, twelve-acre farm in a rural area, and the property’s main residence could be accessed by a driveway that ran from the main residence to a nearby public road. The driveway was approximately 100 meters long, and the entranceway appears to be the closest point at which the presumptive property line ends. Therefore, by limiting the search area to within a 100-meter radius of the main residence, the police virtually ensured that any cell phone activity that met the search’s parameters would have had to come from within the property’s boundaries. Given that the property was privately owned and included “no trespassing” signs, and given that the property owner had claimed that no family member had been to the property between April 4 and April 11, 2020, the chance that the search would result in any unauthorized or unnecessary invasion of privacy rights was almost non-existent. That is, even if the search revealed the cell phone activity of someone who was not involved in the theft, that person would likely have been trespassing on private land.

Even though the warrant did not indicate that the suspect was in possession of a cell phone when the crime was committed, “[i]t is undisputed that cell phones have become an integral part of everyday life…. It is equally undisputed that many, if not most, people carry a cell phone virtually all of the time…. Thus, while there was no direct evidence that the perpetrator in this case had a cell phone or that one was used in relation to the crime, it was reasonable for the issuing judge to infer that the perpetrator was in possession of a cell phone during the commission of the crime and that, consequently, Google had location data and identifying information about that person.”

Further: “As the State correctly notes, a search warrant is an investigative tool, and a valid search warrant may be issued before the police have identified a suspect. So long as the warrant application provides a fair probability that evidence will be found in the place being searched, and so long as the warrant itself is definite enough to ensure that the police can identify the place being searched and conduct the search without any unauthorized or unnecessary invasion of privacy rights, then the probable cause and particularity requirements have been met.”

In sum, we hold that the geofence warrant in the instant case met the basic requirements of the Fourth Amendment. Accordingly, the circuit court did not err in denying Tomanek’s motion to suppress on those grounds.

We caution that this holding is limited to the unique facts before us. Because geofence warrants have an inherent potential for seizure of a profusion of personal device data, issuing courts must remain vigilant in enforcing the underlying probable-cause and particularity requirements of geofence warrants…. For example, courts should be skeptical of discretionary selective expansion, where law enforcement returns to and negotiates with Google instead of a magistrate to seek an expanded search…. Additionally, courts should exercise great prudence in evaluating geofence warrants for heavily populated or congested areas, which have the potential to capture an enormous amount of data from individuals unassociated with the crime. [emphasis in original].

For a recent decision narrowing search warrants of cell phones, see Richardson v. State, 481 Md. 423 (2022), discussed in Discovery From Cell Phones – Differing Civil and Criminal Protocols in Maryland (Nov. 14, 2022).