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.
Wisconsin
Lawyer
