US court finds warrantless tracking of mobile phones unconstitutional

Filed Under: Featured, Law & order, Privacy

Tracking. Image courtesy of ShutterstockThe US government and police regularly pull location data off of cell phone towers or stick GPS trackers on cars to track people and place criminals near crime scenes - often without a warrant.

In what the American Civil Liberties Union (ACLU) calls a "huge victory", an appeals court on Wednesday ruled that such warrantless search violates the US Constitution.

The court - the US Court of Appeals for the Eleventh Circuit, covering Florida, Alabama, and Georgia - ruled that the government illegally obtained Quartavious Davis' mobile phone location data to help convict him in a string of armed robberies in Miami.

The court further stated, unequivocally, that such location data is protected by the Fourth Amendment, which prohibits unreasonable searches and seizures.

From the opinion (PDF), written by Judge David Sentelle:

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.

This ruling comes almost a year after a ruling by the US Appeals Court for the Fifth Circuit, which concluded that location data stored on mobile devices is not protected under the Constitution.

Due to jurisdiction, Wednesday's ruling that such data is in fact Constitutionally protected won't overrule the earlier decision from the Fifth Circuit, but it adds a strong voice to the argument that mobile devices' constant broadcasting of location data should be protected under federal law.

The ACLU, which argued in favor of the eventual outcome in the Davis case, applauded the decision in a tweet:

In huge #privacy victory, appeals court rules collection of cell location info w/out warrant violates #4thamendment

In their 38-page decision, the judges looked at diverse facets of intercepting wireless location data, including both as it regards the content, which they said has already been protected:

... it cannot be denied that the Fourth Amendment protection against unreasonable searches and seizures shields the people from the warrantless interception of electronic data or sound waves carrying communications.

...as well as the implications of tracking a person's location.

With regards to tracking a person's location, the court examined the difference between what can be gleaned over a limited tracking time - you can find that a woman went to a gynecologist, for example - and a prolonged tracking time, which creates a "mosaic" of data points that tells a fuller story: for example, a woman went to a gynecologist and then a few weeks later visited a baby supply store.

The government often relies on such mosaics in cases involving national security. The Supreme Court in the past has observed that in such a context,

...what may seem trivial to the uninformed, may appear of great moment to one who has a broad view of the scene and may put the questioned item of information in its proper context.

What implications might this have for organizations such as the National Security Agency that are using our wireless gadgets to track our movements?

Not much, unfortunately.

Specifically, I'm thinking about how the NSA tracks hundreds of millions of mobile phone locations worldwide.

They'll keep right on doing so, regardless of this ruling, given that the agency has an executive order allowing it to conduct international surveillance as long as it's not constitutionally protected.

Sorry, rest of the world!

Image of tracking map courtesy of Shutterstock.

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7 Responses to US court finds warrantless tracking of mobile phones unconstitutional

  1. Djbrazzy · 43 days ago

    Can somebody explain to me why the quoted tweets in this article and others are copied and pasted immediately below themselves in monospaced font? I'm sure there must be a reasonable explanation, but I'm confused because surely if the initial tweet is illegible due to the device used to read it or some other reason, the rest of the article would be illegible as it's in the same format? I hope I'm making sense here... Other than that thanks Lisa and other Sophos writers, love your articles and have been reading them for months if not years.

  2. Lisa Vaas · 43 days ago

    I've often wondered that myself. I'm checking with the gang to get you a real answer, not just my assumptions about it. Glad you enjoy the articles, though! We enjoy bringing them to you!

    • Lisa Vaas · 43 days ago

      Ah, my assumptions were correct. I'm told that the text version of a visual representation of a tweeted message is for people using graphically primitive equipment: they can't read the image, either because it's not clear enough, won't enlarge usefully, is invisible to their screen reader software (used by the visually impaired, for example), or simply didn't get downloaded.

      • Djbrazzy · 41 days ago

        That makes perfect sense, I'm just confused by the tweet above which is already in plain text... Perhaps the hashtag or links cause problems... Thanks for the answer though.

        • Paul Ducklin · 41 days ago

          Ah! I looked more closely and the reason for your confusion is now obvious :-) The images are mixed up, with the legal decision screenshot directly above the text of the Tweet. Will fix, thanks.

  3. RocRizzo · 43 days ago

    This is good in that it provides a precedent for when we fight them over the data that they are collecting from the police's license plate readers.
    Essentially, they have these cameras on the their cars, that are aiming down at license plates. They then collect each and every license plate number, and its location. This is, in effect, tracking someone's travel, when one can expect some privacy as to what neighborhoods that they are driving through. The police then save this data, and can recall it at any time.
    AFAIC- it's the same sort of thing as tracking a cell phone.

    • Actually license plate tracking is diferent than cell phone tracking in one major point. License plates are publicly viewable (public domain) whereas
      cell phone location is not

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About the author

I've been writing about technology, careers, science and health since 1995. I rose to the lofty heights of Executive Editor for eWEEK, popped out with the 2008 crash, joined the freelancer economy, and am still writing for my beloved peeps at places like Sophos's Naked Security, CIO Mag, ComputerWorld, PC Mag, IT Expert Voice, Software Quality Connection, Time, and the US and British editions of HP's Input/Output. I respond to cash and spicy sites, so don't be shy.