With a recent case, the U.S. Supreme Court had a perfect opportunity to shed some light on the murky—and increasingly important—issue of privacy in the digital age. The court made the right decision, in my view, but the majority's decision sidestepped the compelling social issues presented by the case. So we will have to wait for future decisions—and, no doubt, legislation.

It all started when Washington D.C. police suspected a man named Antoine Jones of being a drug dealer. They got a warrant to place a GPS device on his wife's car, and they subsequently tracked his movements for 28 days. The warrant was good for just 10 days, however, and the GPS wasn't attached until the eleventh day. Moreover, the police tracked the car's movements through Maryland, though the warrant was valid only in Washington. Nonetheless, the police arrested Jones. Prosecutors used the GPS data at trial.

Prosecutors held that the GPS data could be admitted even though it was not covered by a warrant. Their argument was that someone's movements along public streets are public acts, not private, and that Jones had no reasonable expectation of privacy regarding his movements. They pointed out that police cars could follow Jones's car from place to place without a warrant, and argued that the GPS was essentially the same. No warrant, they said, was necessary for the police to record a suspect's movements on a 24/7 basis.

Jones was found guilty, but the case was reversed by the D.C. circuit court. The case wound up in the U.S. Supreme Court as United States v. Jones.

The Supreme Court agreed that Jones's conviction was invalid because the GPS data was collected illegally. The court did not, however, resolve the issue of whether police must obtain a warrant to track and record suspects' locations. Instead, the court concluded that the police erred in placing a physical GPS device on the car. This action, the court concluded, was trespassing. The court did not rule on whether the government could or could not collect round-the-clock electronic surveillance data on citizens who have not been convicted of a crime, without even a warrant.

So an important legal issue remains unresolved. Our cell phones pretty much always know where we are, and our cell-phone providers have access to location data. Internet service providers know the physical locations of our hook-up sites. More and more devices and Web services collect location data on us. In a scary and increasing number of cases, the government is claiming this data without establishing probable cause or securing a warrant. It's a very disturbing development.

The court's decision was unanimous, but justices wrote three opinions. The majority opinion, which outlined the GPS-attachment-as-trespassing theory, was written by justice Antonin Scalia and signed by chief justice John Roberts and justices Anthony Kennedy, Clarence Thomas, and Sonia Sotomayor. A second opinion, written by justice Samuel Alito, was signed by justices Ruth Bader Ginsburg, Stephen Breyer, and Elena Kagan. The opinion likened GPS monitoring to wiretapping phones, and argued that the Fourth Amendment to the Constitution protected citizens from such actions. Justice Sotomayor, who signed Scalia's opinion, contributed an additional opinion in which she argued that the court's ruling that a person “has no reasonable expectation of privacy in information voluntarily disclosed to third parties” was “ill suited to the digital age.” Sotomayor pointed out that people disclose phone numbers and SMS messages to their cell-phone providers, and URLs and e-mail addresses to their ISPs, and the books, groceries, and medications they purchase to online retailers. “I for one doubt,” Sotomayor wrote, “that people would accept without complaint the warrantless disclosure to the government a list of every Web site they had visited in the last week, month, or year.”

I doubt it too. But until the court makes another ruling—or Congress jumps into the issue with legislation—the issue remains unresolved.

Web recommendation: Hey, look—MIT is the new home for Google's App Inventor. The technology lets kids and nonprogrammers create Android apps easily. MIT intends to make App Inventor an open-source project. You can get all the details here. J.D. says check it out.

J.D. Hildebrand has written hundreds of articles for dozens of publications and online communities dedicated to software development. He made a nice potato chowder for lunch today.