A US judge has ruled that looking up a person's movements via mobile phone location data is technically the same as GPS tracking - also recognising that we now have little choice in making much of our private lives public.
Here's a fantastically verbose quote from the ruling of Judge Orenstein, who seems to be a remarkable example of someone who knows what's going on in the modern world:
"The decision in Maynard is just one of several rulings in recent years reflecting a growing recognition, at least in some courts, that technology has progressed to the point where a person who wishes to partake in the social, cultural, and political affairs of our society has no realistic choice but to expose to others, if not to the public as a whole, a broad range of conduct and communications that would previously have been deemed unquestionably private"
In United v Maynard, the previous case Orenstein refers to, the US Court of Appeals for the District of Columbia Circuit ruled that the government must obtain a warrant to track a person's movements via a GPS tracking device. What Orenstein says is that the same rationale applies to re-creating a person's movements using historical cellphone location data - that it's just as intrusive to Americans' reasonable expectation of privacy. In the ruling, Orenstein and the court denied the government's request to access two months of historical mobile phone location data without a warrant from US mobile network Sprint. [Ruling via ACLU and Boing Boing]