GPS devices they installed on the underside of his Jeep with magnets. You see, the police suspected that Pineda-Moreno was growing Marijuana somewhere, and they really didn't like that. Eventually, Pineda-Moreno was arrested and convicted of crimes involving the growth of said Marijuana -- but he appealed the decision because he thought that his Fourth Amendment rights (the one which guards against unreasonable search and seizure) had been violated. The appeals court has recently upheld the original decision, but there were five dissenting votes, meaning that the case is anything but cut and dried. Now, what's obvious is that the police didn't have to traverse into "private" space to attach the tracking device to the suspect's car, but clearly it's debatable -- even as far as the judges are concerned -- what constitutes private and public space. The case is surely not going to end here, so we'll keep you updated. In the meantime, watch your back.