An interesting addendum to this thread is that, apparently, it would be perfectly legal for the US to sell these devices to China for crowd control, despite a law banning arms sales to the region.
The distinction is that, as a ‘non-lethal’ device, the ADS would not be covered by that law. This loophole has recently come to light after China bought several sound-based LRADs (long-ranged acoustic devices) from American company, ATC. By referring to systems like LRAD and ATC only as “devices”, “tools” or “options in the force continuum”, and not “weapons”, they are conveniently kept off the State Department Munitions List and so are eligible for export. This is the same munitions list that famously defined encryption as a “munition” and led to an investigation into PGP creator Phil Zimmerman for arms trafficking, later dropped.
http://www.newscientist.com/blog/technology/2008/05/loudhailer-or-weapon.html
So:
Password protection = weapon.
Device causing intense pain or injury to a person ≠ weapon.
Got it. (Not.)