The Nearer You Get to a Cop, the More You're Slip Sliding Away
The New Scientist introduces us to the "riot slimer"–a device that will allow cops to make any groups of people they don't want standing up, fall down, with air, water, and polyacrylamide powder, which together make a slippery, non-toxic goo.
Sounds like an improvement, at any rate, over such previous non-lethal weapons-against-the-people as tasers or the more recent "magnetic acoustic devices" (sound as a weapon–Kate Bush called it years ago) in terms of heinousness.