There's a bit of a to-do these days about large groups of unidentified drones being reported in New Jersey. Theories abound, from US government tests to foreign powers sending them in from offshore to swarms of domestic drones, some trying to follow others. An interesting aside (underreported) is the group of legal ramifications now being identified. Drone presence is outside a property owner's purview, occuring in FAA-controlled space. Also, it's a crime to damage or destroy any flying vehicle, even a $25 drone. So there seems to be little way to defend against a recalcitrant drone, perhaps even one bearing a grenade. The two thoughts that occur to me regarding defense (other than jamming) would be either to lase various sensors on the drone's frame, or to snare the vehicle with a net or grapple from another drone. Of course, all of the above might be considered illegal interference by the FAA.
As might be the case if one were to hack the control telemetry of the drone, taking over the device and landing it without destruction.
I'm no lawyer, but it looks like there's room for precedent here. Perhaps someone should jam a drone's control communications, hack and land the device and then wait for the owner to file suit. I doubt, after all, that these devices are designed to follow Asimov's Laws Of Robotics, which are as follows (see the story "Runaround" (1942) and later publications like the book "I, Robot"):
(1) A robot may not injure a human being or, through inaction, allow a human being to come to harm
(2) A robot must obey the orders given it by human beings except where such orders would conflict with the First Law
(3) A robot must protect its own existence as long as such protection does not conflict with the First or Second Law
(4 or zeroth) A robot may not harm humanity, or, by inaction, allow humanity to come to harm.
We live in interesting times.
