In the age of cruise-missile assassinations of U.S. citizens without a trial, a Supreme Court victory for civil liberties and freedom is a welcome aberration. Yesterday, a unanimous court ruled in U.S. v. Jones that police don’t have the authority to put GPS tracking devices on vehicles unless they get a warrant first. Yes, you’ve read that right: Until now, the government could and often did mount GPS units on cars and track them without any court’s permission.

Hold off on the celebratory burnouts, however. Even though the unanimous decision appears to be a sweeping condemnation of warrantless vehicle tracking by the government, disagreement among court members about why it was illegal guarantees we’ll have much more surveillance in the near future.

Five of the nine justices said that the government had acted inappropriately and violated the Fourth Amendment—which guarantees our right to be free from unlawful search and seizure—merely because police officers tracked a vehicle by making physical contact with it, without a warrant and without permission. This is clearly insane. The other four justices offered much better reasoning, saying that what the police did was illegal because, regardless of physical contact, they tracked a vehicle for a month without court-given permission in the form of a warrant.

Nonstop, detailed, long-term police surveillance is a search, regardless of whether the police physically touch your vehicle to set it up. And this sort of tracking should require a warrant. These aren’t difficult for police to obtain, and the warrant requirement is in fact waived in true emergency situations.

Make no mistake about it: With the Supreme Court’s decision effectively limited to physical installations of tracking devices on cars, federal and police agencies will be spying on people using other means and without warrants. They’ll flip on OnStar tracking, and they’ll use the GPS embedded in your Audi’s data link. In the future, law enforcement very well could wirelessly download your nav system’s data. Or they might wirelessly eavesdrop on your car’s conversation with the dealership’s computer system in the service bay. Whether or not an agency even notifies OnStar or the dealer or T-Mobile (which provides the data hookups for Audi) that it is using your connection to keep tabs on you isn’t certain—laws on this topic are still being hashed out, too.

The spirit of the Fourth Amendment—and the way it’s been interpreted for the last 50 years—is that the government needs a court-issued warrant when people have what’s called a reasonable expectation of privacy. In other words, while most people think that the government could follow them around for a day—and thus, the government wouldn’t need a warrant—the idea that every single move you make for a month could be tracked is past comprehension. That’s too difficult, too time-consuming, and too expensive for the police to do in all but the most complex cases. Otherwise, it’s not that we expect everything we do in public to be private business, we just don’t expect it to be aggregated into public business.

A judge in a recent case (which took place before this week’s decision, and at a lower court level) said it perfectly: “Disclosed in GPS data will be trips the indisputably private nature of which takes little imagination to conjure: trips to the psychiatrist; to the plastic surgeon; to the abortion clinic; the AIDS treatment center; the strip club; the criminal-defense attorney; the by-the-hour motel; the union meeting; the mosque, synagogue or church; the gay bar; and on and on.”

And it’s not just where you go. GPS data can include recordings of how you drive, too, from acceleration to top speeds to how many g’s you pull through a corner. “Hooning,” as some of our friends writing at other blogs would say, can be quantified and recorded.

Many of the justices writing in U.S. v. Jones seem to understand that rapid developments in technology are changing the workings of laws governing privacy, warrants, and police surveillance. But courts are by definition reactive bodies. In the interim, the police and other government agencies are going to take every technological opportunity presented to conduct investigations. They shouldn’t be blamed for doing what they think is best to fight crime. Often, though, investigators’ desire for expediency is going to mean that police don’t even pick up the phone to get a judge’s OK.

There’s a valuable lesson from the defeat of SOPA and PIPA, two intrusive internet bills that were just killed in Congress after public outcry. Just as Google and Wikipedia lent legitimacy and lobby power to opponents of SOPA—people who wanted to keep the internet free from government intrusion—those of us opposed to this sort of unchecked tracking will also need the backing of a major industry. We should call on automakers to side with us in this arena. After all, it’s their technology that the FBI and other government officials eventually will be commandeering to track us.

As Benjamin Franklin once said, “Those who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.”

Read more at Car and Driver blog:

Smile! Your Car's on Cop Camera

States That Use Cameras to Monitor Your Driving

Automotive Spyware: Vehicle Tracking Systems and Data Recorders Tested