Score One For The 4th Amendment: Appeals Court Says Police Need A Warrant To Track Phone Users' Location

from the big-win dept

A very big and important ruling came out yesterday in the 11th Circuit appeals court, saying that police need to get a warrant to track someone’s location (via their mobile phone locations). This is a big deal, as we’ve been discussing for years. Many state courts have issued similar rulings, but many federal courts had gone the other way. While a few district courts had agreed that a warrant was needed, having an appeals court say so is a big deal.

In this case, the defendant, Quartavius Davis, was accused of a bunch of crimes, involving robbing a bunch of stores. Among the variety of evidence against him was cell phone location data — specifically 11,606 location records. Davis argued that the data was collected without a warrant, violating his 4th Amendment rights (he also has other issues with the way the case was handled and challenges some other aspects as well, but we’ll focus on the 4th Amendment issue concerning his location data). The court notes that other courts are still struggling with this issue, and looks to the Supreme Court’s famous ruling in the Jones case, involving whether or not a warrant is needed to attach a GPS device to a car. As we noted then, that ruling stopped short of really examining if gathering up location data required a warrant, though some of the side opinions (mainly the concurrence by Justice Sotomayor) discussed the idea. This ruling looks back at some history around the 4th Amendment, and the evolving view concerning “trespass theory” vs “privacy theory,” before digging into Jones. The Jones case, you may recall, was decided on the idea that putting the device on the car was a form of “trespass,” leaving aside the privacy aspect. But, obviously, this case is different. Thankfully, the court takes some instruction from the concurrences that do discuss privacy theory, and see how they apply in this case.

But, in an important way, the court seems to go even further. While much of the focus in the Jones case was on the “mosaic theory” of linking together a bunch of individual location data points to create a picture that reveals something people expected to be kept private, this ruling notes that even a single data point may be enough to violate the expectation of privacy:

One’s cell phone, unlike an automobile, can accompany its owner anywhere. Thus, the exposure of the cell site location information can convert what would otherwise be a private event into a public one. When one’s whereabouts are not public, then one may have a reasonable expectation of privacy in those whereabouts. Therefore, while it may be the case that even in light of the Jones opinion, GPS location information on an automobile would be protected only in the case of aggregated data, even one point of cell site location data can be within a reasonable expectation of privacy. In that sense, cell site data is more like communications data than it is like GPS information. That is, it is private in nature rather than being public data that warrants privacy protection only when its collection creates a sufficient mosaic to expose that which would otherwise be private.

The court also rejects the idea that the information is not private just because it puts the defendant near the scene of a crime:

The prosecutor at trial stressed how the cell phone use of the defendant established that he was near each of six crime scenes. While committing a crime is certainly not within a legitimate expectation of privacy, if the cell site location data could place him near those scenes, it could place him near any other scene. There is a reasonable privacy interest in being near the home of a lover, or a dispensary of medication, or a place of worship, or a house of ill repute. Again, we do not see the factual distinction as taking Davis’s location outside his expectation of privacy. That information obtained by an invasion of privacy may not be entirely precise does not change the calculus as to whether obtaining it was in fact an invasion of privacy.

And, finally, the court addresses the famed “third party doctrine” issue, of whether or not Davis gave up his right to privacy to this information because it’s been “given” to a third party (i.e., the mobile phone operators). The court is not convinced and (thankfully) explains how Smith v. Maryland (that key case that so many third party doctrine claims rely on) doesn’t make sense here, relying on a ruling from the 3rd Circuit, stating that because Davis did not “voluntarily” shared this information with the mobile operator, the third party doctrine does not apply (amusingly, the court even cites the government’s own arguments to support the lack of a voluntary handover):

The reasoning in Smith depended on the proposition that “a person has no legitimate expectation of privacy in information he voluntarily turns over to third parties,” …. The Third Circuit went on to observe that “a cell phone customer has not ‘voluntarily’ shared his location information with a cellular provider in any meaningful way.” That circuit further noted that “it is unlikely that cell phone customers are aware that their cell phone providers collect and store historical location information.” … (emphasis added). Therefore, as the Third Circuit concluded, “when a cell phone user makes a call, the only information that is voluntarily and knowingly conveyed to the phone company is the number that is dialed, and there is no indication to the user that making that call will also locate the caller.” … Even more persuasively, “when a cell phone user receives a call, he hasn’t voluntarily exposed anything at all.” ….

Supportive of this proposition is the argument made by the United States to the jury. The prosecutor stated to the jury “that obviously Willie Smith, like [Davis], probably had no idea that by bringing their cell phones with them to these robberies, they were allowing [their cell service provider] and now all of you to follow their movements on the days and at the times of the robberies . . . .” Just so. Davis has not voluntarily disclosed his cell site location information to the provider in such a fashion as to lose his reasonable expectation of privacy. In short, we hold that cell site location information is within the subscriber’s reasonable expectation of privacy. The obtaining of that data without a warrant is a Fourth Amendment violation.

That said, the court still decides to not overturn the original ruling, saying that the court ruled in good faith. However, it still means that future cases will require a warrant for this information (within areas covered by the 11th Circuit). It seems likely that this, or another similar case in a different circuit, will eventually make it to the Supreme Court, but this is a very good ruling in the meantime.

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Comments on “Score One For The 4th Amendment: Appeals Court Says Police Need A Warrant To Track Phone Users' Location”

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Anonymous Coward says:

I imagine they will still track cell phones just like they always have, the only difference, now, is that the data gathered will not be allowed as evidence in a court of law. So if they really want to use it as evidence they will have to post date the warrant. I assume that is still illegal, although I do not recall a ruling saying so. I would not surprised if a particular interpretation of the law would allow such evidence tampering.

Anonymous Coward says:

So why would the US not require in future that all cellphones (and other similar electronics) be sold with a notice that informs the purchaser that use of the device, including merely carrying it, may result in third parties being able to obtain the location of the phone, and that the purchaser is responsible for informing all users of the device capability? Then the location data would be ‘voluntarily disclosed’ and there would be no expectation of privacy. Isn’t it arguable that all cellphone users *should* be informed that they are leaking data?

Anonymous Coward says:

Re: Re:

Careful, if that argument flies, you will have no privacy exceptions when using any communications medium, as in if you use a phone or the Internet you are making what you do available to third parties and the government, including all the contents of calls, as you have been advised by your provider..

John Fenderson (profile) says:


the court still decides to not overturn the original ruling, saying that the court ruled in good faith. However, it still means that future cases will require a warrant for this information

Can anyone explain this to me? I don’t understand how this is a reasonable part of the ruling. If a court rules in error, but made that ruling in good faith, that means that the court’s ruling won’t be overturned? I thought that overturning ruling was about correcting errors made in good faith or not. If the need for a warrant applies to future cases, why would it not apply to the case that is being appealed?

This makes no sense.

Anonymous Coward says:

Re: Huh?

? good faith.

Can anyone explain this to me?

First, read through United States v Leon (1984). The is the case the Eleventh Circuit cited.

Then, note Orin Kerr’s commentary at Volokh.

Finally, on the exclusionary rule, the Eleventh Circuit managed to misapply Leon in a way that seems to replicate the result of Illinois v. Krull, which held that the good faith exception applies to good faith reliance on a statute that authorizes a search later found unconstitutional. I think the Eleventh Circuit ultimately gets to the result that is correct under Krull. But it would have been better for the Court to find Krull and apply it directly rather than come up with tortured logic to justify that outcome based on the very different case of Leon.

So you might want to read Krull, too.

John Fenderson (profile) says:

Re: Re: Re:2 Huh?

No, they don’t. They write in legalese. Legalese only superficially resembles English in the sense that what the words literally say often mean something different than what they mean in court opinions and legal contracts. That’s one of the main reasons why we need lawyers: to translate legal documents into English.

And yes, I was hoping that someone could explain it to me so I can avoid having to spend the hours necessary to decode what the courts actually said. If you don’t want to help me out, that’s fine. Call me lazy if you like, but my request isn’t unreasonable.

TheResidentSkeptic says:

only the telco needs the information

And only for billing – to figure out the portions of a call, or calls handled outside their home network (those pesky extra “roaming charges”). Once that has been done, the records can be deleted. And should be. The actual tower data could be anonymized to the network ID for that call segment… they don’t actually need the exact transceiver ID – let alone the geo-coordinate triangulation from the 3 tower points they have now.

John Fenderson (profile) says:

Re: only the telco needs the information

And E911. The towers are legally required to be able to physically locate a given phone to within 50 meters. Most modern phones do this with GPS (that cannot be disabled). Some do this with tower triangulation. Further, the location must be stored so that the last known location can be pulled up should the caller make a 911 call but the location can’t be determined for some reason.

Anonymous Coward says:

And tens of thousands of cases could now be overturned

And now, just like I’ve been saying for years, if this ruling is upheld potentially tens of thousands or hundreds of thousands of convictions could now be overturned because of illegally gathered location tracking evidence from cell phones being used to get the conviction.

I’ve been saying for years that the DOJ and states were playing with fire by continuing to insist they don’t need a warrant they could have easily gotten to use cell phone evidence to convict people of crimes. The DOJ and states will have wasted billions of tax payer dollars and millions of prosecution hours if they have to put over a hundred thousand people back on trial again because of this.

Just because the government can say “but we’ve been doing it this way for long that it would be a massive expense to change the rules now” doesn’t mean the courts will decide to ignore the 4th amendment out of practicality.

nasch (profile) says:

Re: And tens of thousands of cases could now be overturned

I’ve been saying for years that the DOJ and states were playing with fire by continuing to insist they don’t need a warrant they could have easily gotten to use cell phone evidence to convict people of crimes.

If these were legitimate searches, they could easily get warrants for them. Which means either the DOJ is just catastrophically lazy, or they know they’re off the rails on a lot of these searches and don’t want a paper trail showing what they’re doing.

Anonymous Coward says:

Eating food to survive is completely voluntary. Nobody is forcing you to eat it, unless you’re in Gitmo. Just like filling out medical forms at the doctors office is voluntary if you want medical treatment. Oh wait, they’re not voluntary at all.

The 3rd party doctrine is a insidious assault on human rights. It interprets mandatory and voluntary as having the exact same meaning, even though they’re actually complete opposites. That’s the twisted genius behind the 3rd party doctrine law.

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