"Legal drone delivery may still be a ways off, but quadcopters have been smuggling contraband into prisons for years now. Quadcopters are cheap enough and powerful enough to carry a few pounds of goods, like cigarettes, knives, cell phones, or drugs over a prison fence, and they're sometimes even recovered from the drop to do it again. Prisons, which understandably don’t want drones to do this, are now looking for ways to keep the robots out."