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SD Supreme Court Rejects Warrantless GPS Tracking

In positive Fourth Amendment news, the South Dakota Supreme Court this week reversed a drug conviction and declared that police need a warrant to use GPS transmitters to secretly track citizens.

According to the unanimous ruling in South Dakota vs. Elmer Wayne Zahn, Jr., police had plenty of reason to think Zahn was dealing marijuana. They'd found lots of spare cash and containers smelling of pot in the bedroom where Zahn's wife died in June, 2008. In November 2008, police arrested Zahn for DUI and found marijauna and $10,000 in cash in his car. That stop resulted in Zahn's pleading guilty to DUI and possession of pot and paraphernalia.

Then in March 2009, Aberdeen policeman Tanner Jondahl attached a magnetic GPS tracker to Zahn's vehicle. Police tracked Zahn's every vehicular movement for 26 days, including several trips to two storage units and a trip to Gettysburg, which was a bad idea, since Zahn was out on bond at the time and wasn't supposed to leave Brown County. Oops. The police rearrested Zahn, got a search warrant for the storage units, and found in one of them a hidden freezen with pot. That evidence led to another conviction, including intent to distribute.

Zahn appealed that conviction, saying the court should have thrown out the evidence discovered thanks to the GPS tracking. Our justices agreed:

...The GPS device used in this case continuously transmitted the geographic location of Zahn's vehicle to a computer at the Brown County Sheriff's Department. It enabled officers to not only determine his speed, direction, and geographic location within five to ten feet at any time, but to also use the recorded information to discover patterns in the whole of his movements for nearly a month.

[¶28.] When the use of a GPS device enables police to gather a wealth of highly-detailed information about an individual's life over an extended period of time, its use violates an expectation of privacy that society is prepared to recognize as reasonable. The use of a GPS device to monitor Zahn's activities for twenty-six days was therefore a Fourth Amendment search under the Katz "reasonable expectation of privacy" test [South Dakota v. Elmer Wayne Zahn, Jr., South Dakota Supreme Court, opinion filed 2012.03.14].

Cops can still watch what you're doing in public. They can still follow you down the highway in the cruiser. But the Court sees a problem with moving beyond observing individual public movements and secretly gathering a comprehensive picture of every move citizens make.

Police can still use GPS tracking devices; citing U.S. v. Garcia, the justices say that "The Fourth Amendment 'cannot sensibly be read to mean that police [should] be no more efficient in the twenty-first century than they were in the eighteenth' century." However, to conduct such a thorough search, police must first get a warrant.


  1. Nick Nemec 2012.03.16

    Imagine that a warrant, what a novel idea!

  2. Rorschach 2012.03.16

    If the Supreme Court had ruled otherwise, who would or could prevent the government from tracking anyone, with or without suspicion of criminal activity?

  3. Les 2012.03.16

    All cell phones now track us regardless of warrants or not. Why would the gov need any more than our cell number which shows on our banking statements whether credit card or checking. They have all the tracking equip they need.

  4. caheidelberger Post author | 2012.03.17

    Les, that's actually one of the minor reasons I balked at getting a cell phone for years, and why I still don't regularly carry mine. The technology is different from GPS, so it may not be as accurate or non-stop as the GPS bug attached to Zahn's car. This court decision doesn't stop police from obtaining the information, but it does prevent them from using that information in court, making that information much less valuable.

  5. Stan Gibilisco 2012.03.17

    On Friday, I joined the hysterical herd at Best Buy in Rapid City for the opening gong, at which time I and five or six other lunatics stampeded through the doors and grabbed our new iPads.

    I spent the better part of the next 24 hours playing with the doggone thing. It's the first Apple I've had in 30 years. (My first one was an Apple II-Plus in 1983.) One or two of the setup questions had to do with tracking: Did I want the device to keep track of my whereabouts, or not? I decided to say no.

    However, I would like to throw a twist into this mix. Suppose that the government had a way of monitoring the whereabouts of every single one of us, every single moment of the day, every single day of the year, down to, say, the nearest meter or two on the surface of the earth, and perhaps even altitude above sea level to the nearest meter ...

    In that event, were you to stand accused of a crime you did not commit because you were not on the scene, you could instantly show that you were not there. Those who accused you could easily face charges of perjury -- were they stupid enough to accuse you in the first place.

    I don't want to advocate government monitoring of our activities, especially without our knowledge or consent. But given the choice between knowingly accepting total surveillance of that sort and rejecting it, in this day of false allegations and unjustly ruined reputations, I might just say okay, go ahead and follow me, and if you die of boredom, don't say I didn't warn you.

    Oh, I got a black one, 16 GB, Wi-Fi only. The simplest of the best, I guess.

  6. caheidelberger Post author | 2012.03.17

    From Apple II+ to iPad3? Wow! There's a poem in that, or maybe a podcast!

    But now, dear Stan, you complicate my 4th-Amendment absolutism with a practical society-wide cost-benefit analysis. I wonder how many innocent people we could save as you hypothesize through universal surveillance. Would kidnapping become impossible? Might there never be another child's face on a milk carton? Would no one ever spend three days lost in the mountains surviving on nibbles of jerky and Angry Birds?

    But then what liberty would we lose in exchange for that security?

  7. Les 2012.03.17

    I'm just thinking Stan, I could hack your pad and put you in the the center of suspicion!! I don't really think you were at Lewie's on the night in question.

    These cell phones really have us, what was that saying??...."stewed, screwed and tattooed."

    Corey, check your info on cell phone GPS, I believe it to be 3D GPS as my aircraft GPS is.

  8. caheidelberger Post author | 2012.03.18

    Ah, the benefits of universal surveillance would only be as good as the reliability and security of the technology. Shall my freedom hinge on the durability of an electronic impression? (Our finances do!)

    Do all phones have satellite GPS, Les, or do they just use the triangulation from tower signals?

  9. Les 2012.03.18

    Triangulation of some aspect was used in the past, these are now gps receivers in all cell phones sold today. I may be wrong Corey, I thought I was wrong once, but I was mistaken.

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