[chordalkeyboard]

> if you placed it there with the intent to trap someone who you expect to be looking at your computer, you may well be liable if their computer blows up

Liable for what? You haven’t promised that the code is safe, and they chose to run it.

> there's no significant difference from active retaliation

There is a significant difference, in active retaliation you choose to attack someone elseks computer, with a trap file the attacker chooses to run files they have stolen from you. Big difference.

> You'd be just as liable as for physical boobytraps on your property, with pretty much the same reasoning.

The reasoning is different, lethal or injurious man traps are prohibited because you don’t respond to trespassing with lethal force and you don’t know who or what may trigger the trap. Man traps that lock the intruder in a room without injuring them are fine, and used in high security installations.