In a case decided last week, United States v. Jones, the Supreme Court said that police need a warrant to attach a GPS device to your car and track everywhere you go for an extended period of time. The decision is most surprising for its unanimity—all nine of the justices agreed that the police needed a warrant—although the Court split on the reason why.

Generally speaking over the last couple decades, the Court has given law enforcement leeway to do what they want. In this case, though, the Court ruled that the police trespassed onto Antoine Jones’ property—his car—in order to attach a GPS device; the trespass was a “search” and required a warrant. In the past, the Court has rejected the argument that a trespass is a search.

Justice Scalia wrote the Court’s opinion, but he joined six other justices in rejecting that notion in a 1987 case. Apparently, hopping multiple fences, standing on private property, and shining a flashlight into a barn is perfectly okay for law enforcement, but attaching a GPS device to a car parked in a public parking lot is an unacceptable trespass. Personally speaking, a tiny GPS device attached to my car is way less intrusive than having multiple officers run around on my fenced-off property. I don’t think there is a way to reconcile these two cases. The Court just doesn’t trust new technology.

The Court has shown its reservations with new technology before. For example in Kyllo v. United States the Court reversed a drug conviction because the government used a thermal imaging device, without a warrant, to look at Danny Lee Kyllo’s home. The thermal imaging device in use didn’t reveal much private information. It just showed inchoate, shapeless blobs of heat. But the Court didn’t trust the newfangled device and said the government needed a warrant to use it.

Last week’s decision is good news for those of us concerned about privacy. The Court hinted it may have ruled the same way even if the police never attached a GPS device to Mr. Jones car. Because of advancing technology, the day may soon come where everyone can be tracked endlessly, without a trespass ever occurring. The company Google is nearly there right now, and if private citizens can do it, the government won’t be far behind.