In the Fifth Circuit Court of Appeals, that conception of privacy has been rejected. Its judges noted that the Fourth Amendment confers not a general right to privacy, but protects citizens against certain kinds of government intrusion. But isn't government intruding into my affairs profoundly regardless of whether it monitors my movements directly or tracks them via a third party?

Without a warrant, the government can now obtain what is, for many Americans, an extremely detailed record of their daily movements. Doesn't that violate "the right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures"?

I'd say so. Alas, Supreme Court precedent still dictates the use of this highly arbitrary "reasonable expectation" test. As the appeals court decision puts it:

We understand the cell phone users may reasonably want their location information to remain private... But the recourse for these desires is in the market or the political process: in demanding that service providers do away with such records... or in lobbying elected representatives to enact statutory protections. The Fourth Amendment, safeguarded by the courts, protects only reasonable expectations of privacy.

Sonia Sotomayor's words from a case on GPS tracking are apt: "I would ask whether people reasonably expect that their movements will be recorded and aggregated in a manner that enables the Government to ascertain, more or less at will, their political and religious beliefs, sexual habits, and so on." Her notion of what's reasonable is far more likely to be shared by Americans.

At least they used to reasonably expect that they wouldn't be subject to intrusive tracking. Now Americans are beginning to expect that the government will surveil them in any way that it pleases, sometimes publicly, other times in secret. According to the Times, the Fifth Circuit ruling "is likely to intensify legislative efforts, already bubbling in Congress and in the states, to consider measures to require warrants based on probable cause to obtain cellphone location data." With the courts standing by as the Fourth Amendment is gutted, legislative fixes are long overdue.