A federal court has ruled that warrantless cell phone tracking by police is legal.

The U.S. Court of Appeals for the Sixth Circuit yesterday ruled (PDF) that law enforcement officials were within their legal right to track Melvin Skinner, an alleged drug trafficker, through his cell phone before his arrest in 2006. According to court documents, law enforcement officials were able to use the GPS feature on Skinner's cell phone to track his whereabouts and eventually arrest him.

According to the court, Skinner was convicted of two counts of drug trafficking and another of conspiracy to commit money laundering. Soon after, he appealed the conviction, saying that it violated his rights under the Fourth Amendment, which is designed to protect citizens from unreasonable search and seizure. Judge Rogers, one of the two judges in the three-judge panel to rule in favor of the decision, had this to say in his opinion:

"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."

The court's ruling stands in stark contrast to a ruling made earlier this year by the U.S. Supreme Court on GPS tracking. The high court ruled in a unanimous decision that law enforcement agencies must obtain a warrant in order to place a GPS tracking device on a vehicle. In the Skinner case, the judges argue, the feature is built directly into cell phones, and thus doesn't require physical interaction on the part of law enforcement.

"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," Judge Rogers wrote. "This is not a case in which the government secretly placed a tracking device in someone's car."

The Sixth Circuit Court's ruling follows an earlier opinion laid down by the Third Circuit in 2010, arguing that warrantless cell phone tracking is admissible under law. The Obama Administration has been vocal in its agreement with the court's ruling, saying that Americans have no "reasonable expectation of privacy" when it comes to their cell phones' whereabouts.

Several organizations, including the American Civil Liberties Union, the Electronic Frontier Foundation, and the Center for Democracy and Technology, argue that a warrant is required for cell phone tracking, as prescribed under the Fourth Amendment.

Judge Donald, the only dissenting voice in the Skinner case, tends to agree with that argument, saying in the opinion that "acquisition of this information constitutes a search within the meaning of the Fourth Amendment, and, consequently, the officers were required to either obtain a warrant supported by probable cause or establish the applicability of an exception to the warrant requirement."