This gun is made by a UK company called Selectamark, and it can fire non-lethal pellets that look like flat green marbles. This ammo can leave a DNA trace mark that can enable the authorities to see who was at a scene of a crime.
Let me give you an example. Let’s say there is a riot, and the police can’t figure out who is responsible. If, during the riot, a policeman were to fire this tagging gun at the most culpable, it would leave a mark on them that would be intact after three weeks. So if the suspect was arrested during that window, the biological mark would refute any false testimony of not being at the scene of the crime.
Think of it like one of those dye-packs that they use on stolen money. I would have to say that I’m not certain if I like the idea of this, as it feels dystopian. It reminds me of the Judge Dredd film, the one with Stallone, where his gun takes a DNA sample of the shooter every time it is fired.
Who knows whether or not this will ever get implemented. I guess the bigger question is whether or not you want to live in a society that uses these.