Congress has always been slow to recognize the privacy implications of new technologies. Unauthorized wiretapping wasn't outlawed until 1967, 91 years after "Mr. Watson, come here, I want to see you," and 77 years after Louis Brandeis and Samuel Warren's famous Harvard Law Review article on the importance of privacy as a legal concept. As Rosen writes in The Unwanted Gaze, "The politics of privacy tends to be largely reactive, fired by heartstring-tugging anecdotes that capture the public imagination." Not until after The Washington City Paper published Judge Robert Bork's video-rental records in 1987, for example, did Congress pass the Video Privacy Protection Act, which outlawed that kind of disclosure. At the intersection of privacy and technology, the legislative wheels require considerable grease to start turning.

There's also a substantial anti-privacy lobby, composed of industry front groups that view tough privacy laws as potential revenue killers. The Online Privacy Alliance and the Privacy Council may sound like muckraking Naderite organizations, but they're pure "Astroturf," fake grass-roots lobbies that hammer home the message that privacy restrictions hurt American business.

Law enforcement likewise views privacy laws as an impediment, especially now that it has grown accustomed to accessing location data virtually at will. Take the MetroCard, the only way for New York City commuters to pay their transit fares since the elimination of tokens. Unbeknownst to the vast majority of straphangers, the humble MetroCard is essentially a floppy disk, uniquely identified by a serial number on the flip side. Each time a subway rider swipes the card, the turnstile reads the bevy of information stored on the card's magnetic stripe, such as serial number, value, and expiration date. That data is then relayed back to the Metropolitan Transportation Authority's central computers, which also record the passenger's station and entry time; the stated reason is that this allows for free transfers between buses and subways. (Bus fare machines communicate with MTA computers wirelessly.) Police have been taking full advantage of this location info to confirm or destroy alibis; in 2000, The Daily News estimated that detectives were requesting that roughly 1,000 MetroCard records be checked each year.

A mere request seems sufficient for the MTA to fork over the data. The authority learned its lesson back in 1997, when it initially balked at a New York Police Department request to view the E-ZPass toll records of a murder suspect; the cops wanted to see whether or not he'd crossed the Verrazano Narrows Bridge around the time of the crime. The MTA demanded that the NYPD obtain a subpoena, but then-Justice Colleen McMahon of the State Supreme Court disagreed. She ruled that "a reasonable person holds no expectation of confidentiality" when using E-ZPass on a public highway, and an administrative subpoena—a simple OK from a police higher-up—was enough to compel the MTA to hand over the goods.

What McMahon was advancing, in effect, was an extension of the rationale behind the rules governing "pen register" and "trap and trace" surveillance of phone lines. While police need a warrant to listen in on the content of calls, they do not need judicial warrants to monitor the phone numbers a person calls or is called from. The phone company already knows what numbers you are dialing, and their existence as a knowing third party means that you should not expect this data to be kept private—or so the logic goes. On the Verrazano Narrows Bridge, how could a toll transaction between a driver and the MTA be private, since the bridge is a public space with a zillion other drivers (third parties all) around to witness it? It doesn't take a genius to see how this argument could be extended to location data obtained through E911; if the emergency operator can get access to your GPS coordinates, how can you expect privacy? It's not like the cops are asking to know what you talked about, only where you were.

The 2002 Washington State case State v. Jackson is perhaps the only other instance of the use of location data being contested on appeal, and the conclusion was similar. In the absence of laws specifically addressing GPS, the court ruled that the police didn't need a warrant to attach a tracking device to a suspect's vehicles. The vehicle was in plain view, and the cops weren't intercepting any "communication"; in other words, the tracking conformed to the "trap and trace" standards. Never mind the obvious stretch of applying wiretap laws from the 1960s to such a novel technology.

Any time the police are allowed to act without obtaining a judicial warrant, it is natural to be concerned about whom they're accountable to. How much evidence must a detective present before he or she is given access to someone's subway habits? How easy would it be for the men and women of the 10th Precinct, right behind my apartment in New York City, to find out that I'm fond of taking the F train to East Broadway on Sunday mornings? How about the GPS data from my Motorola? The NYPD's lips are apparently sealed about this matter; despite repeated phone calls and a formal written request, spokesman Detective Walter Burnes did not respond to questions.