Ars Technica reports on cases concerning warrantless access to cellphone location data:
Courts all over the country have been wrestling with this question, and the government has been on something of a winning streak. While one court ruled last year that such information requests violate the Fourth Amendment, most others have reached the opposite conclusion.
The Obama administration laid out its position in a legal brief last month, arguing that customers have “no privacy interest” in CSLR held by a network provider. Under a legal principle known as the “third-party doctrine,” information voluntarily disclosed to a third party ceases to enjoy Fourth Amendment protection. The government contends that this rule applies to cell phone location data collected by a network provider.
While this may be a plausible reading of previous precedents, the practical implications are alarming. While CSLRs are not as detailed as data that can be gathered via GPS, months of data can still reveal a host of sensitive information about a person’s movements. If the third-party doctrine allows the government to obtain such information without a warrant, that’s a strong argument for re-considering the third-party doctrine. […]
In addition to arguing that the location data it was seeking was too coarse-grained to raise privacy concerns, the government also argued that it was legally irrelevant. That’s because under the third-party doctrine, customers give up privacy rights in any location data they voluntarily disclose to a third party. And the government believes that customers do this every time they allow their cell phones to communicate their location to cell phone towers. […]
This argument has a puzzling circularity to it. After all, it’s equally true that customers “voluntarily” disclose the contents of their phone calls to the phone company when they make a call using a cell phone. And yet the contents of voice communications are protected by the Fourth Amendment.