Scenario is that a county property owner shoots down a drone with his shotgun that flies over his property. Is that a crime? Is there a right of ownership that extends into the air as a possible defense? Like a trespass...

I mean... it might be disorderly conduct, deadly conduct, or criminal mischief depending on the facts. It's also just as possibly something you could cram in to the language of an ill-fitting criminal statute but really fits better as a civil action if someone wants to play that game to get a new drone.

How about a forfeiture by wrongdoing style defense? Did the drone operator register, including affixing identification as required?

http://knowbeforeyoufly.org/register-your-drone/

The flight of airplanes in navigable airspace is not normally a trespass. U.S. v. Causby 66 S.Ct. 1062 (1946). HOWEVER. Causby says that a trespass will lie when the overflights substantially interfere with use and enjoyment. One of the factors that Causby uses in that analysis is the height of the overflight. Considering that drones are required by FAA rule to operate under 400 vertical feet, there's a pretty good argument that it would be a trespass even under Causby, if it happened on a repeated basis.

Your drone operator may also have a legal problem. Texas has some of the most restrictive drone regulations in the nation.

See Tx Govt Code:

http://www.statutes.legis.stat...cs/GV/htm/GV.423.htm

The FAA says it's a federal offense, same as shooting at any aircraft.

Drone Shooting is a Federal Offense

Here's the statute they cite.

18 USC § 32

Anyone care to lay odds on whether someone actually gets prosecuted federally?

"“aircraft” means any contrivance invented, used, or designed to navigate, or fly in, the air."

Under the broadest reading of the federal law, it would be a federal offense to bat a paper airplane out of the air...

Not weighing in pro or con, but did read this yesterday:
Woman Shoots Drone

http://arstechnica.com/tech-po...perty-with-one-shot/