Not long ago we applauded the D.C. Circuit Court of Appeals for making the right call in prohibiting police use of Global Positioning System technology to conduct surveillance without a warrant.

Now we have a ruling by the 9th Circuit Court of Appeals that faced the same issue and came up with just the opposite conclusion.

This issue appears headed for the U.S. Supreme Court, where we hope the justices uphold the first opinion and require police to go before a judge, just as they would to get a wiretap.

In the most recent case, the judges allowed police to install a tracking device, reasoning that people have no expectation of privacy when they are driving around or even when their cars are parked in their driveways.

When it comes to observing public behavior that anyone could see, they are right. A police officer does not need a warrant to follow a suspicious-looking car. But when you introduce technology that can simultaneously capture all the movements of a large number of people, this practice becomes something else entirely.

It’s easy to see how this technology could be misused. Last month an unnamed company contacted the state to see if it could install GPS devices in financed cars on behalf of lenders. The federal government wants all cell phones to have GPS so that emergency personnel can trace 911 calls.

Applications like these could create massive databases recording our every move unless there are strict rules about how this information can be gathered and used.

As technology brings us into a new era, it’s up to the courts to update our laws. We think that means treating this type of electronic “watching” with the same care as we do electronic “listening,” which means not permitting it without a warrant.