system
Given the following post, respond as if you're commenting on Reddit:
human
[Fantasy/International Law] Would a legion of the undead be considered a biological weapon under international law?

Purely hypothetically, if a brilliant but misunderstood genius (with a wholly justified grudge against the world and a deep loathing for all humanity) were to raise an unstoppable horde of reanimated corpses driven purely by dark magic and a hatred for the living, would their use be considered in violation of the Geneva Protocol?

In this entirely hypothetical situation, our unconventionally yet ruggedly handsome hero would have begun his merciless war of annihilation against all mankind by taking over a small central European nation, gaining recognition from the UN, and then unleashing a magical plague against his own populace that transforms then into unholy nightmares of rotting flesh and dark malice. If I - I mean, if he were then to engineer a border dispute with the nation next door, would he be able to use these creatures without drawing international censure, economic sanctions, and possibly even UN intervention?

And if, despite his brilliance, he were to somehow lose his war against all that breathes beneath the sky, would a decent lawyer (I know, I know, "decent lawyer". Just my little joke) be able to get me off any ensuing charges of Crimes Against Humanity, or would the use of foul necromancy be considered a violation of the international protocols prohibiting the use of biological and bacterial methods of warfare?
gpt
If this were virus-zombies I'd say yes, but as it's 'dark magic and a hatred for the living' zombies, I'd say strictly no (with caveat).

The geneva protocol covers the 'Prohibition of the Use in War of Asphyxiating, Poisonous or other Gases, and of Bacteriological Methods of Warfare'. Although the cadavers may be biological, the protocol was never written with necromancy in mind.

That said, just as the advent of chemical, biological and nuclear weapons precipitated in the international community regulating and/or banning them, the UN and similar groups would likely condemn the use of unconsenting-necromancy/reanimation in wartime and ban it post facto.

edit: if you're looking for a legal defence you can pull out of the bag after the effect, your best bet is to rely on 'creepy magic' reasons - say he was totally innocent and being controlled by geas or threat by some extradimensional bad guy, or evil souls or whatever.