A non-lethal, crowd-control weapon that is still under development. The Active Denial system focuses a beam of energy that penetrates just enough of a person’s skin to cause receptors to go off and cause great pain to the receiver without causing permanent damage. Think of people running away in fear, not knowing what is happening to them. Off course, it wouldn’t be non-fatal if they jumped off of high places or trampled down others in that state of panic.
It sounds like an excellent tool for torture, though I’ve always thought that the fear of permanently losing functionality of an organ was the most effective means of torture. Again it would work best if the “torturee” didn’t know anything about it.
Other uses I can think of include securing vaults and sensitive areas though I’m sure someone would come up with an effective armor against the beam. Tin-foil anyone?