CDT has uploaded the amicus brief filed by itself, EFF, Matt Blaze, Andrew J. Blumberg, Roger L. Easton, and Norman M. Sadeh in United States v. Jones, a case that asks whether a warrant is required under the Fourth Amendment to attach a GPS device to a vehicle.
You can read the brief here. As I understand it, there seems to be two main arguments in their brief: (1) that GPS is not equivalent to beeper technology, which simply augments an officer’s sensory capabilities; and (2) the massive amounts of detailed information compiled automatically by GPS systems violates the public’s sense of still having some reasonable expectation of privacy in public.
Briefs, documents, and more background on the case can be found on SCOTUSblog.