Massachusetts Supreme Court Tackles Law Enforcement Use Of Cell Tower Dumps

from the collect-it-all dept

Years after they’ve become a go-to tool for law enforcement to work their way backwards to suspects, the Massachusetts Supreme Court is wrestling with the issue of cell tower dumps.

Cell tower dumps can often be had with only a subpoena. They give investigators access to all cell phones that were in the area of the tower at certain times. Investigators peruse these lists of numbers to try to find numbers that might be linked to someone who committed a crime. The problem is investigators don’t know who that “someone” is, so they, however briefly, turn everyone in the area into a suspect.

The Third Party Doctrine tends to control this collection of data. The information is collected as a necessary part of cell phone operation. Therefore, there’s no expectation of privacy in this information, the theory goes, since users are aware service providers need this information to provide service. And it very well may be that cell users are aware of this. What they generally don’t expect is that law enforcement can obtain this data without a warrant, or, indeed, obtain it at all when investigators don’t even know who they’re looking for.

The thorny issue of tower dumps is before the court, which now has the US Supreme Court’s Carpenter decision to consider as well, something it didn’t have prior to June 2018. In that decision, the Supreme Court says there was an expectation of privacy in cell site location data, which tower dumps are, even if they contain information on hundreds or thousands of people, rather than the more targeted collection of cell site location info related to a single targeted number.

The Carpenter decision was rather narrow, holding that use of cell site location info to track people’s movements requires a warrant. But it also stated clearly that there’s an expectation of privacy in these records, whether or not they’re collected long term or once via a tower dump. The tracking was the issue here, but Carpenter changed how courts view cell site location info.

The state of Massachusetts has its own constitution to factor in as well. And in some cases, state constitutions have proven more protective of rights than the US Constitution, which is considered to be the floor for rights, rather than the ceiling.

Thomas F. Harrison covered the oral arguments in the Massachusetts Supreme Court for Courthouse News Service. And from what’s reported here, it appears the justices aren’t all that keen on pretending working backwards from untargeted data dumps isn’t the sort of thing the public expects to be happening with the phone records they generate simply by taking their phones wherever they go.

“Doesn’t society have an objective expectation that you’re not going to be caught up in a police search in this way,” Justice Scott Kafker asked, noting that “the idea that 50,000 people are potential suspects is a bit much.”

While the justices seemed to think the police met strict constitutional standards in this case, they also worried that allowing the government to indiscriminately sweep up location data for hundreds or thousands of innocent people could lead to a dystopian result.

“It’s a slippery slope,” said Justice Dalila Wendlandt. “You could find out if a person was home at 4 a.m., or if he was in a Catholic church at 10 a.m. on Sunday.”

She added: “If you had enough data points you could put together a very good picture of Justice Wendlandt’s private life.”

“You could see if a person was at a political event or other association,” fretted Justice David Lowy.

The underlying case involved a lot of phone records. Six robberies and zero suspects led police to obtain tower dumps from near those locations, resulting in the collection of nearly 51,000 phone records. From that, police tracked down one suspect, Jerron Perry, who is charged with murder because someone was killed during one of the robberies. Perry challenged the tower dump evidence, which was rejected by the trial court, leading to this appeal to the state Supreme Court.

But this case may not go Perry’s way. Unlike countless other cases, a warrant was actually obtained to collect this data. The question is what’s the limit to collections obtained with warrants. Does a warrant whose only probable cause is that it’s likely the service provider has these records still abide by the Constitution? Perry’s representatives and entities filing amici briefs say this goes too far, making it something closer to the “general warrants” the US Constitution aimed to eliminate.

At this point, it’s unclear how the justices will lean. Some, like those listed above, seemed concerned about what this does to the expectation of privacy. Others, however, did not see the warrants as “general,” noting that not all warrants need to be particularized to a person. They also noted the only towers “searched” were those near the scenes of robberies, which (somewhat) particularized the searches, even if the cops had no idea who they were looking for.

And one justice said the facts of this case allowed the police to slide on one underdeveloped probable cause assumption.

Justice Serge Georges was troubled that the police simply assumed that the perpetrator had a cellphone.

“The government gets past first base without showing that a cell phone was part of the crime,” he said. “There’s just this notion that everyone has a cellphone, and it’s on. That’s just bald speculation. We have no reason to think the person who committed these crimes had a phone. We’re just going to assume. That’s the part that really bugs me.”

That is concerning. Given what’s known about how often investigators start investigations with phone records — along with how easily they can be obtained — some criminals are probably leaving their phones behind when committing crimes. The government should have more to work with than an assumption that might be incorrect, especially when that assumption allows them to collect data in bulk.

If the court decides warrants can’t be used to collect bulk data, it will be a significant privacy win for residents of the state. It will also be the first of its kind in the nation — a prohibition on the untargeted collection of cell site location info.

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Comments on “Massachusetts Supreme Court Tackles Law Enforcement Use Of Cell Tower Dumps”

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Anonymous Coward says:

Typo: one too many negatives

And from what’s reported here, it appears the justices aren’t all that keen on pretending working backwards from untargeted data dumps isn’t the sort of thing the public expects to be happening with the phone records they generate simply by taking their phones wherever they go.

"isn’t" should be "is"

That Anonymous Coward (profile) says:

"We have no reason to think the person who committed these crimes had a phone."

But everyone has one…
And a Facebook…
And an Insta…
And a Twitter…

And has NEVER EVER watched a crime procedural where the cellphone leads to catching the bad guy because he was to stupid to know it was a homing beacon.

Of course the next thing they should really worry about is how much of these dumps are they retaining for checking for others things unrelated to this case but it might be evidence they can use in other things.

Upstream (profile) says:


did not see the warrants as "general," noting that not all warrants need to be particularized to a person.

4th Amendment: "The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized."

I realize the wording in the first quote is the author’s (Tim cushing) but he seems to be very directly referring to the reasonong of some of the Justices.

Throw in what TAC mentioned, which implies a complete lack of "reasonable suspicion" or "probable cause," and I think these cell tower dumps are a serious violation of the poeple’s rights, both as specified by the text of the 4th Amendment, and as implied by it.

Never mind that the Third Party Doctrine is itself a vile abomination and flies in the face of the most basic concepts of an individual’s right to privacy, which, while never specifically addressed in the Constitution, underlies significant portions of it.

Anonymous Coward says:

Re: Particularly?

You wrote "particularly" in italics, but seem to have missed that it’s followed by "describing the place to be searched"—which does not say it needs to be "particularized to a person". The text that follows makes it clear the warrant can refer to "things to be seized" rather than people to be seized.

Whether the warrant actually described the place to be searched (presumably, either computers at several towers or one central server at each telco) accurately isn’t clear.

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