I'm not typically a gun person, but this seems like a really flawed idea. As the article describes it, it's a gun that only works against an unprepared enemy. Anyone with an RF jammer could completely stop its use, if I understand it correctly. It wouldn't be much more complicated to make a device that could pick up its frequency from a distance and use it on a stolen weapon either. Of course some cryptographic exchange between the watch and the gun would fix that, but it still doesn't prevent you from jamming it.

In cases like many school shootings, where the gun was stolen ahead of time, all it does is require the culprit to steal the watch too. A physical key (old-fashioned or cryptographic) would do the same thing but more reliably.

The term "smart gun" brings to mind a development that I think most users of HN would agree is a bad idea. Making a gun that tries to automatically determine who's authorized to shoot whom, like a Dominator from Psycho-Pass, seems to open up a whole mess of problems. Making more reliable non-lethal weapons is the direction I'd rather see the problem attacked from.