Those old reruns of "The Wire" I've been working my way through, in which seemingly at least once a season Baltimore police used the latest GPS tracking gadgets to follow a bad guy, just wouldn't be the same had they been written after Monday, when the Supreme Court ruled that its unconstitutional for police to use GPS tracking devices without a search warrant.

Sort of.

In effect, the court ruled that it's okay for police to track every move you make. The only thing wrong they did in this particular case was commit common trespass when they applied a tracking device to a car. And future courts in future cases are free to rule differently.

"This approach is ill suited to the digital age... I for one doubt that people would accept without complaint the warrantless disclosure of every Web site they had visited in the last week, or month, or year."
The court's ruling was essentially a non-ruling, leaving the GPS case open for future interpretation. The majority opinion, written by Justice Scalia, in the 5-4 decision ruled that police in Washington, D.C. trespassed and violated a suspected drug dealer's protection from unreasonable search and seizure when they applied a GPS tracking device to his wife's car.

But that does not mean, the majority said, that in the future police may be able to apply a tracking device that does not rely on an unconstitutional trespass. All of this highlights something that has come up in several recent tech cases that have gone before the high court: the document, written in the 18th century, is showing its age.

Even the gadgets in "The Wire," new and cutting edge when the show began its run on HBO a decade ago, are showing their age. In a concurring opinion, Justice Alito noted that very problem: if current case law is having trouble keeping pace with technological advances, then surely the Fourth Amendment is coming up short.

"In the pre-computer age, the greatest protections of privacy were neither constitutional nor statutory, but practical... The surveillance at issue in the case - constant monitoring of the location of a vehicle for four weeks - would have required a large team of agents, multiple vehicles and perhaps aerial assistance," Alito wrote. "Only an investigation of unusual importance could have justified such an expenditure of law enforcement resources."

Or, as Rebecca J. Rosen notes in her excellent analysis of the ruling in The Atlantic, "Today, we need law to make up for the protections that technological difficulties once provided." Alito went on to suggest that the issue may need to be handled with legislation by Congress, much as the legislative branch took the lead on updating wiretapping laws in 1986.

Justice Sotomayor's concurring opinion goes even further, hinting that the Fourth Amendment may need a complete re-imagining. Sotomayor said the third-party doctrine of Fourth Amendment law, in which you can't have a reasonable expectation to privacy when you voluntarily share information, needs to be rethought.

"But today we share information with a third party (often Google) with every email we send, every document we store in the cloud, and nearly every website we visit," Rosen wrote in The Atlantic. "Sotomayor writes that 'This approach is ill suited to the digital age... I for one doubt that people would accept without complaint the warrantless disclosure of every Web site they had visited in the last week, or month, or year.' Instead she says, we need to stop treating 'secrecy as a prerequisite for privacy'."