Article from State Bar of Wisconsin -
www.WisBar.org, 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.