(This post contains spoilers for Avengers: Age of Ultron. You have been warned.)
In first two parts of this series, I examined whether Tony Stark and Bruce Banner could be held liable for the damage caused by Ultron (probably) and whether Ultron itself could be (probably not under real-world law, possibly in the Marvel Cinematic Universe). Now we turn to what actually happened in the movie: Ultron was defeated by the Avengers and the last copy of his mind was destroyed by the Vision. From a real-world point of view we have one non-human entity destroying another in a fictional foreign country (Sokovia). I have no idea what Sokovia’s legal system is like or whether it would recognize either the Vision or Ultron as legal persons. So I’m going to punt and apply US law, assuming that both the Vision and Ultron are regarded as legal persons in the MCU.
I. The Facts
After destroying all but one of Ultron’s bodies and burning out his connection to the internet, the Vision confronts Ultron’s last remaining body, itself badly damaged. After a brief repartee, Ultron attempts to attack the Vision and is promptly killed.
The Vision’s only defense here is self-defense. He knew that this was Ultron’s last body and that he could no longer escape to the internet. He and Ultron were alone in the woods, so the damaged Ultron-body did not pose a threat to anyone else, nor could it realistically flee. Necessity and duress generally do not excuse homicide. The killing was intentional. So self-defense it is. But would it work?
Ultron did make an aggressive motion toward the Vision, so at least some degree of self-defense could be excused, and the attack was imminent. But homicide in self-defense is generally only allowed if a reasonable person would believe it necessary to prevent one’s own imminent death or serious bodily injury. It’s questionable whether a single badly damaged Ultron-body could threaten serious injury to the Vision. Thus, while the Vision could have defended itself, it may have overstepped by destroying Ultron outright.
Some jurisdictions recognize “imperfect self-defense” as a mitigating defense in cases where the defendant (i.e. the Vision) had an honest but unreasonable belief in the necessity of lethal self-defense. This would bring the charge down to something like manslaughter instead of murder. But in most jurisdictions it would just be murder.
With the caveat that this all happened in a fictional country and represents new legal territory, things don’t look good for the Vision. The argument for self-defense is pretty weak., and it’s difficult to see what happened as anything other than an extrajudicial execution of Ultron after he had ceased to be a meaningful threat.