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    Wisconsin Lawyer
    May 01, 2004

    Recent GPS Cases

    Recent cases nationwide and in Wisconsin recognize the power of Global Positioning Systems. With the increased accuracy of GPS technology, more lawyers are using -- and courts are admitting -- GPS evidence. Learn how GPS can affect your case.

    David Schumann

    Wisconsin Lawyer
    Vol. 77, No. 5, May 2004

    Recent GPS Cases

    Law involving GPS evidence is in its infancy because prior to May 2, 2000, the U.S. government programmed inaccuracies into civilian GPS readings of anywhere from 300 feet up to several miles,1 which hampered GPS use as an evidentiary tool. Cases rejecting GPS evidence recorded prior to May 2, 2000, should not bar admission of much more accurate GPS evidence collected after May 2, 2000. With GPS accuracy currently at about 15 feet, and three feet for WAAS-enabled receivers,2 accuracy issues are only relevant on a case-by-case basis.

    The following are recent GPS cases:

    • People v. Sullivan, 51 P. 3d 1181 (Colo. 2002) (GPS stalking conviction upheld regardless of any proof that defendant downloaded or accessed GPS tracking information).
    • State v. Pirsig, 670 N.W.2d 610 (Minn. 2003) (GPS data used for agriculture field management also used to convict worker of crop theft).
    • Avena v. Department of Natural Resources, 858 So. 2d 697 (La. App. 2003) (GPS data used to estimate damages to oyster beds for compensation).
    • State v. Clifton, 158 N.C. App. 88, 580 S.E.2d 40 (2003) (OnStar GPS system used to capture thief and recover vehicle purchased with fraudulent certified checks. The thief was captured in the vehicle with blank checks and check drafting equipment).
    • State v. Green, 567 S.E.2d 505 (S.C. 2002) (GPS data used to establish distance of "drug free zone" around school to convict drug manufacturer).
    • U.S. v. McIver, 186 F.3d 1119 (1999) (court approved warrantless use of GPS tracking and beeper tracking, attached in defendant's vehicle in his own driveway, to lead officers from a marijuana plot in a national forest to the defendant's home. The court reasoned: 1) there was no reasonable expectation of privacy in the driveway; 2) public GPS attachment on the undercarriage was not a "search"; 3) there was no evidence the undercarriage was concealed from the public; 4) no "seizure" occurred because there was no meaningful interference with defendant's possessory interest in the vehicle).

    In addition, GPS tracks are being used to prosecute Flemington, New Jersey, police officers for misconduct and records falsification; the officers signed logs stating they were performing security checks at locations at which the GPS disclosed they had not been. (The Express-Times, Nov. 20, 2003).

    On Feb. 17, 2004, an AP story reported that California Judge Delucchi, after two days of testimony, decided to allow GPS tracking evidence of Scott Peterson's vehicles in the Lacy Peterson murder trial. The court found GPS technology "generally accepted and fundamentally valid," in spite of the less than perfect track submitted by the prosecution.

    1These programmed inaccuracies, known as "Selective Availability," were used to prevent an enemy from using our own GPS technology against us. Apparently by 2000, our potential enemies either had their own GPS system (like Russia) or could use our GPS signals in such a way that the programmed inaccuracies only hampered citizens. In addition, the U.S. discovered other ways to deny use, such as selective GPS jamming and GPS "spoofing" (sending false GPS signals in a specific area) to throw off enemy accuracy.

    2The WAAS system corrects for atmospheric distortions of signals and therefore gives better GPS accuracy.

    So You Want to Track Yourself?

    Want to track your own movements, prove your billable travels, make sure you're not lost, or just get familiar with GPS before that critical case walks in your door? While most GPS receivers will work to create admissible evidence, there are a few minimum requirements you should consider:

    Track Memory. Your GPS must have the ability to record its position to memory, the longer, the better. This is measured in Trackpoints, minimum: 1,000, preferred: 10,000. Ability to adjust the track recording frequency is a plus, because you can predict when to download the track to your computer.

    Computer Port/External Power Port. GPS track data has no evidentiary value if you do not download it to a computer or transfer it over the cell system to the Internet. Some GPS sources, like OnStar or GPS phones, may have no user accessible track information. An external power port allows the user to track beyond battery life _ if the batteries run out, the track will end.

    Computer/Power Cable. This usually costs extra, but buy one now to have when you need it.

    Software. After connecting your GPS to the computer, download the raw data on G7ToWin (freeware, www.gpsinformation.org/ronh/) to make sure you have the critical information. Then you can display the GPS evidence on programs such as USAPhotomap (freeware) to display the information on topographic maps and aerial photos, or GarTrip (shareware) for time, speed, and mileage information.

    Waterproof. GPS rarely works indoors, so what good is a unit that can short out after getting wet? For best results, make sure the GPS is waterproof to three feet for 30 minutes.

    For product reviews, information on GPS features, and links to GPS dealers, go to http://gpsinformation.net/. Sporting goods stores and general retailers carry a few models, but seldom have staff with the expertise to guide your buying decision. Geocaching, a sport in which GPS users locate caches in the wild using GPS coordinates, is a good way to practice GPS skills.


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