Federal Court Says Cell Tower Dumps Violate The Fourth Amendment

Things continue to change thanks to the Supreme Court’s Carpenter decision. Prior to that, it was assumed the Third Party Doctrine justified all sorts of data dragnets, so long as the data was held by a third party. But that doctrine assumed the data being grabbed by law enforcement was being handed over knowingly and voluntarily. The Carpenter decision pointed out this simply wasn’t true: cell tower location data is demanded from all cell phones in the tower coverage area and location data (along with identifying info about the device itself) was taken, rather than volunteered.

This has led to a number of interesting decisions, including a couple of state-level court decisions regarding mass collections of cell tower location data. Cell tower dumps generate records of all cell phones in certain areas during certain times, the same way geofence warrants work, but using more accurate cell site location info (CSLI).

Now, even with a warrant, courts are finding cell tower dumps to be unconstitutional. In 2022, the top court in Massachusetts said these warrants may still be constitutional, but only if law enforcement followed a stringent set of requirements. Earlier this year, a magistrate judge in Mississippi came down on cell tower dumps even more forcefully, declaring that if geofence warrants (those seeking Google location data) were unconstitutional, then it just made sense warrants seeking more accurate data with a similarly-sized dragnet also violated the Fourth Amendment.

Those rulings are limited to those states (and, in the case of the magistrate judge, likely just limited to his jurisdiction). But now there’s something at a much higher level, which is definitely headed to a showdown at the Ninth Circuit Appeals Court as soon as the DOJ gets around to appealing this ruling. Here’s Matthew Gault, reporting on this decision for 404Media.

A Nevada man, Cory Spurlock, is facing charges related to dealing marijuana and a murder-for-hire scheme. Cops used a tower dump to connect his cellphone with the location of some of the crimes he is accused of. Spurlock’s lawyers argued that the tower dump was an unconstitutional search and that the evidence obtained during it should not be. The cops got a warrant to conduct the tower dump but argued it wasn’t technically a “search” and therefore wasn’t subject to the Fourth Amendment.

U.S. District Judge Miranda M. Du rejected this argument, but wouldn’t suppress the evidence. “The Court finds that a tower dump is a search and the warrant law enforcement used to get it is a general warrant forbidden under the Fourth Amendment,” she said in a ruling filed on April 11.“

The government tried to argue that if the warrant was unconstitutional, it didn’t matter because this really wasn’t a search under the Fourth Amendment. It hinted the Third Party Doctrine applied instead. The court disagrees, citing the expert for the defense, who pointed out not only was the data not voluntarily handed over to cell service providers, but even the de-duplicated list of responding devices turned this into an extremely broad search.

Spurlock’s expert Ms. Guay examined the same records Investigator Pelichowski got in response to warrant 20-SW-56 in preparation for the Hearing and clarified a few important evidentiary points for the Court. First, she demonstrated that, while Investigator Pelichowski does not appear to have done this in his investigation, from the tower dump records, she was able to determine roughly where the various phones listed in the data were and could plot them on a map if she wanted to. Second, she determined that after accounting for de-duplication the tower dump records contained records—again, including rough location information—for 1686 unique phones. Third, she clarified that the wireless company users whose phones showed up in the tower dump data did not opt in to sharing their location with their wireless provider, and indeed, could not opt out from appearing in the type of records received in response to warrant 20-SW-56.

Even if further efforts were made to eliminate false positives, it’s too little too late. A warrant can’t be salvaged because things were done after the warrant had been served and information obtained. It’s a general warrant, says the court, precisely the thing the Fourth Amendment was erected to protect against.

Taken together, the Court agrees with Spurlock that these characteristics of warrant application 20-SW-56 render it equivalent to a request for “access to an entire haystack because it may contain a needle.”

Now, the bad news, at least for Spurlock. Pretty much every judge involved, along with the investigators who crafted the warrant, had almost zero experience in handling cell tower dump warrants. (I suspect that this is because, prior to Carpenter, most law enforcement agencies handled this with subpoenas that weren’t subject to judicial review. On the other hand, this happened in a sparsely populated area where double murders aren’t exactly common, so there may have never been a reason to use one before.) Since everyone appears to be breaking new ground here, the good faith exception applies. No evidence is suppressed.

But this holding stands going forward, which means Nevada law enforcement will need to be a lot more careful when crafting cell tower dump warrants or, better off, avoid them altogether and get back on the right side of the Fourth Amendment’s particularity requirements. Since this requires federal and local law enforcement to be better at their jobs, it’s safe to assume the DOJ will ask for this ruling to be overturned. Until that happens, the law of the land is clear: Cell tower dumps (and geofence warrants) are unconstitutional.