Cellphones and Privacy

[Commentary] Cellphones have long been a fixture of life, becoming more powerful and more "aware" of their locations every year. Phone companies and software developers jump on each advance to provide new services. But the law is behind the technology.

Many people have no idea how much data their cellphones collect about them. Phones, for example, report back to the carriers on where the users are at any given time — in some cases even when the phone is not in use. When you carry a cellphone, you are "essentially carrying a tracking device," says Jennifer Granick, the civil liberties director of the Electronic Frontier Foundation. Those records are a treasure trove for law enforcement. The police can ask phone companies to monitor the movements of a suspect in real time. Or they can request stored records on a customer's movements in the past weeks, months or even years.

It is this historical data that is at issue Friday in a federal appeals court in Philadelphia. Information about a person's movements is by nature extremely private. It can reveal where they attend religious services and what political meetings or protests they are involved in. It can provide evidence of marital infidelity. If the courts allow the government to obtain these records without probable cause, the impact on ordinary people's freedom will be substantial.