discharging projectile is not quite legal, but a catty shot is nowhere near as severe as a firearm. you do have recourse if such a short distance is taken, you would however have to identify the operator to the satisfaction of authorities.

Which law? Is there an FAA rule concerning minimum drone height over someone's property? I understand there's generally a maximum of 400 feet for drones, but I don't know about any rules for minimum height.

Wow, these rules are incredibly poorly defined. I'll take the bit that says "20-30 feet high with propeller guards over a small family gathering in the park wouldn’t necessarily require any additional documentation" to mean that flying 30 feet in the air over people is legal. And people can definitely throw a rock 30 feet high.

yes its all very weaselly, the wieght class of the drone, and the participation of those people in the drone usage is considered as well.

this allows you to film your own family & friends enjoying a picnic, but not endanger, harass, annoy or intimidate some other group, from enjoying thier lives

in context this is about ireland and private property so to be purist about -on topic, we need to look at EU rules regarding flights over homes and yards.