Via Engadget (which does a good job of explaining the case), an anonymous reader passed us a link to a GPS Tracking Systems Blog post. The site, which reports regularly on GPS-related news, has word that on-the-sly GPS tracking is legal for officers of the law. A 7th circuit court of appeals ok'd the use of a GPS device in apprehending a criminal. Though the defendant's lawyers argued on fourth amendment grounds, the judge found GPS tracking did not warrant an 'unlawful search and seizure'. The judge did warn against 'wholesale surveillance' of the population, though, so ... that's some comfort.