Pilfered Wi-Fi Is No Shield From Prying Eyes of Police

Internet-service subscribers can't hide from police behind their IP addresses, the numbers assigned to devices connecting online. Now a federal court in Pittsburgh has ruled that people who piggyback on their neighbors' Wi-Fi networks forfeit privacy too.

The ruling, issued this month, was the first to address the Fourth Amendment rights of such people and the latest to shed light on technologies used by police to locate criminal suspects. The amendment protects against unreasonable searches by the government, requiring that police get search warrants when suspects have reasonable expectations of privacy. The case also raises questions about people who connect to the Internet through public wireless-access points. Police have to use special software to identify Wi-Fi interlopers because they squat on the same IP addresses as paying subscribers. The central question in the Pittsburgh case, which is headed to a federal appeals court, is whether police can use such software without obtaining a search warrant.