Under current Fourth Amendment doctrine, parties to a communication enjoy constitutional protection against government surveillance only when they have a reasonable expectation of privacy in those communications. This paper discusses the insufficiency of the reasonable expectation of privacy test in the context of modern communications. Significantly, courts have required that communications media be virtually invulnerable before affording them Fourth Amendment protection.
http://stlr.stanford.edu/2007/06/a_first_principles_approach_to.html
First Principles of Communications Privacy by Susan Freiwald
Under current Fourth Amendment doctrine, parties to a communication enjoy constitutional protection against government surveillance only when they have a reasonable expectation of privacy in those communications. This paper discusses the insufficiency of the reasonable expectation of privacy test in the context of modern communications. Significantly, courts have required that communications media be virtually invulnerable before affording them Fourth Amendment protection.