Since this seems to be a growing problem, legislation is being put forward to address privacy issues as well as countermeasures. It appears that the FAA is involved and is classifying these as "aircraft" and shooting one down, even if it's peering in your bedroom window can get you in hot water. That is presuming the owner fesses up to that, but simply flying over your privacy fence while your old lady (or daughters) is sunbathing certainly is offensive, that, in the eyes of the law at this point does not justify downing it, and again, hot water.
I think a trained Peregrine would be more entertaining anyway and a plausible solution. Might get by with that, too. It will get sorted out, because (it's already been done) they can be weaponized. Saw a vid of a 9mm mounted on one. Shooting that one I'd not hesitate and call a good lawyer. Should be able to get away with that.
To me, it's virtual trespassing and should be treated the same. The things have cameras (eyes) so the operator can read signs just the same as if they were on foot right at your fence. Many have been shot down, and many people are fighting their right to do so. In fact, if I remember correctly I read that it has become somewhat a sport in CO to go drone hunting. Bad publicity, but it may provide the needed push to get it under some kind of control.
There is also the problem of LEO use of drones. How would that play out in court I wonder. You might someday get the law to let you shoot them down in general, but when the law is using them so sniff out a meth lab, how are you supposed to differentiate that from a nosy, or malicious operator invading your privacy?
I think it is legal to net them, and hold them until the owner contacts the law and you get a visit and a chance to explain. Just not legal to destroy someone else's drone, even in your own airspace, which is part of why the FAA is getting involved.