When I boarded an Amtrak train this summer, I had no idea what kind of ride I was in for.

Upon arrival at my home stop in Connecticut, I realized that my iPhone was missing. I still had hope, though. Apple's free Find My iPhone service uses GPS, Wi-Fi and cellular information to locate lost i-gadgets on a map. After a couple of days, Find My iPhone e-mailed me to announce that it had found my phone—a map revealed it to be at a house in Seat Pleasant, Md.

Well, great. How was I going to retrieve a phone five states away? On a nutty whim, I posted a note to my Twitter followers about my lost phone. “Find My iPhone shows it in MD. Anyone want to help me track it down? ADVENTURE!” And I included a map showing the green locator dot over a satellite image of a nondescript house.

Within an hour the quest to recover my phone was on blogs, Twitter, and even national newspapers and television shows. “Where's Pogue's phone?” became a high-tech treasure hunt.

Using the address provided by Find My iPhone, local police got involved. The homeowner confessed to stealing the phone—no doubt baffled as to how the police had known exactly how to find him. And a day later I had the phone back. (I decided not to press charges.)

To me, that was that. Modern tech + good old-fashioned police work = happy ending, right?

Not for everyone. Lots of people were disturbed by the affair. They saw my posting the thief's address as a gross violation of his privacy.

“Are there to be ANY limits in this country?” wrote one reader. “Mr. Pogue … not only … crowdsourced instant ‘deputies,’ giving [them] detailed maps of the device's location but got the police to go to that location. That location is someone's home. What's the presumption of privacy there?”

My initial thought was: “Wait a minute—we're expressing sympathy for the thief?” When you steal something, don't you risk giving up some rights? How was my Twitter post any different from the “wanted” posters of suspects' photographs that still hang in post offices?

Of course, the difference in this case is that I, not law enforcement, posted the map and began the chase. Does that constitute a breach of the thief's rights? Is this a slippery slope into a world where the Internet's citizens become digital vigilantes?

Those are tricky questions. Even when the government or law-enforcement agencies want to get cell location information, the law is not always clear-cut. Sometimes the police require a warrant to obtain such information from cell phone companies; in other instances, they do not. In my case, there's not even much law to guide us, says Chris Soghoian, a privacy researcher at Indiana University Bloomington. A bill proposed last year in Congress, nicknamed the GPS Act, would have addressed “find my phone” services, saying that it's “not unlawful” for the owner of a stolen phone to use geolocation information to help an investigation.

It is possible, Soghoian says, that I violated some kind of state harassment or stalking statute. For the most part, however, both the legal and ethical ramifications of my crowdsourced phone quest are nothing but murk. It would have been better if I had been able to recover the phone without blasting a photograph of the guy's home to the Internet at large. It would have been better if he hadn't taken my phone at all or had responded to the “Reward if found” messages I sent to its screen. Yet combining the powers of geotracking and social networking seemed such an obvious tactic that, at the time, I hardly gave it a second thought.

In the end, maybe what society really needs is an app called Find My Moral Compass.

Apps to find your lost phone: ScientificAmerican.com/nov2012/pogue