> If annexation by force is no longer a legitimate means of acquiring land, then it is reasonable to say that it was never legitimate. If it is, then going to war to take territory is still possible. But there really is no fair way to declare a fixed epoch and say that forceful annexation was only legitimate in the prior era, and is now unacceptable in the following era.

There's something to be said for systems that, more-or-less, are practical and work without making perfect logical sense or being perfectly self-consistent.

Building a perfect legal regime has a lot in common with building a perfect software application.