The Electronic Privacy Information Center has filed an amicus brief in the GPS tracking case.
The United States Supreme Court will hear arguments on November 8 to determine whether the warrantless use of a GPS tracking device by the police violates the Fourth Amendment. EPIC filed a "friend of the court" brief in US v. Jones, urging the Supreme Court to uphold robust Fourth Amendment protections.
Here's a quote from the Amicus brief itself -
In this context, the proliferation of GPS tracking technology creates a large, and largely unregulated, repository containing detailed travel profiles of American citizens. Law enforcement access to such information raises the specter of mass, pervasive surveillance without any predicate act that would justify this activity. Constitutional protections against unreasonable searches are intended to protect individuals from this precise sort of government intrusion.
The full text is at.