If you lost your very own version of Apple’s most iconic mobile device, the aptly-named “Find My iPhone” app can help you find it, and has indeed led thousands of would-be-victims to thieves. But that presents problems. What if they don’t want to give it back?

“It opens up the opportunity for people to take the law into their own hands, and they can get themselves into really deep water if they go to a location where they shouldn’t go,” San Francisco district attorney and former police chief George Gascón told the New York Times.

There are many success stories, for example the case of Sarah Maguire, a 26-year-old yoga instructor who tracked her phone to an exurb of Los Angeles and got it back without incident. But cautionary tales also abound. For example the one about a New Jersey umpire who attacked a man on an iPhone, thinking it was his device. (It wasn’t.)

If you’ve lost your phone, officials recommend contacting the police. It is less advisable, they suggest, to arm yourself with a hammer, as this guy did.

All this would be more of less moot with the use of a kill switch, which could render your phone useless to a thief. But debate has sprung up around this issue–the Cellular Telecommunications & Internet Association (CTIA) insists that kill switches aren’t necessary, as covered yesterday (May 5) in Popular Science.

Over at Digital Trends you’ll find six more stories of vigilantes who used “Find My iPhone” to, well, you know.