Obviously we are all in way over our heads debating international law. So is Dave, which is why I hope this doesn't go on for long.
  • It may matter under law if the orbs are considered flotsam or jetsam. If the orbs were deliberately discarded by aliens, they may belong to Sydney. If the alien ship crashed, they belong to the aliens. If the aliens fired the orbs at earth to destroy the dinosaurs that's jetsam but with ill intent; it'd be like asking for your cannonballs back from a ship you sank.
  • Mexico's legal claim is weaker, I suspect, if the orbs are not the product of humans living in what is now Mexico.
  • I'm pretty confident that the United States would not agree to send a very powerful super to live in a Mexican museum for the rest of her life. The power imbalance between the US and Mexico is pretty large in the real world, and in this world where the US has organized a whole team of supers, it's worse.
  • I'm also pretty confident that "Oh well, the orbs belong to Mexico and since they can't be separated from Sydney, she belongs to Mexico as well" would not hold up in a US court or in the Hague. There's some pretty strict laws and treaties about slavery.
  • What's likely to happen is that Arianne uses her super powers, arguably for good, and finds a loophole that allows Sydney to keep the orbs. Perhaps the US government can write Mexico a check with enough commas in it to placate them.
  • Since Sydney can't be separated from the orbs, and was worried clear back in the early strips about being studied in a lab for the rest of her life, I don't much blame her for smuggling them out of Mexico. It doesn't make things better if the lab is in Mexico.