Privacy advocates aren't going to like this one, but a 2-1 ruling in the U.S. Circuit Court of Appeals for the Sixth Circuit has given law enforcement officials the legal right to track suspects by cell phone in real-time without first obtaining a warrant. The ruling revolves around a case in which Melvin Skinner, a convicted drug trafficker, sought to have his charges dismissed on the basis that his arrest ran afoul of the Fourth Amendment.
According to court documents (PDF), Skinner transported illegal drugs between Arizona and Tennessee. DEA agents were able to track Skinner's location using data emanating from his pay-as-you-go cell phone, which ultimately led to his arrest in a motorhome filled with over 1,100 pounds of marijuana.
"When criminals use modern technological devices to carry out criminal acts and to reduce the possibility of detection, they can hardly complain when the police take advantage of the inherent characteristics of those very devices to catch them," the judges wrote in their ruling. "This is not a case in which the government secretly placed a tracking device in someone’s car. The drug runners in this case used pay-as-you-go (and thus presumably more difficult to trace) cell phones to communicate during the cross country shipment of drugs. Unfortunately for the drug runners, the phones were trackable in a way they may not have suspected. The Constitution, however, does not protect their erroneous expectations regarding the undetectability of their modern tools."
Part of the ruling comes down to interpreting Skinner's ignorance of pay-as-you-go cell phones. The analogy the court used is that of dog hounds, suggesting that Skinner can't be entitled to rely on the expected untrackability of this tools (cell phone), otherwise it would be like saying dog hounds would not be allowed to track a fugitive if the fugitive was unaware the dogs had his scent.